Looking Glass not detected on 2017 MacBook Pro


I got my Looking Glass today and tried hooking it up to my MacBook Pro with no luck - the LEDs came on, but the display was never detected. I disconnected all other accessories, rebooted, connected the USB cable before the HDMI, and then the HDMI before the USB all without success. This is a MacBook Pro with 4 USB-C ports and I tried with 2 different adapters.

Here are the specs:

MacBook Pro 15-inch, 2017
Processor: 3.1 GHz Intel Core i7
Memory: 16 GB 2133 MHz LPDDR3
Graphics: Radeon Pro 560 4096 MB

Adapter 1:
Apple USB-C Digital AV Multiport (https://www.apple.com/shop/product/MJ1K2AM/A/usb-c-digital-av-multiport-adapter?fnode=8b)

Adapter 2:
HyperDrive USB-C Hub (https://www.amazon.com/HyperDrive-Type-C-Adapter-50Gbps-MacBook/dp/B01MUAEI7J)

I’m not sure what to try next.

Not detected on any device as a screen, Black Screen

Hi Jay,

Did you see the MAC screen flicker ( the screen go black for half a second and then back on ) when HDMI cable plug in? If you don’t see the flicker, possibly the HDMI has poor connection. Could you please plug and unplug the HDMI cable to see if it can connect properly?


No, I don’t see a flicker.

Yes, I’ve tried unplugging and replugging and even tried a different HDMI cable (one that’s usually connected to a 4K monitor so I know that it’s working).


Hi Jay,

It looks that the USB-C to HDMI adapter may not support 2560X1600 @60Hz. Could you please test it on a Windows machine or MAC pro which has a native HDMI port?



I’ve connected the display to a PC and the Looking Glass is working - so it appears that it’s just not working with my Mac HDMI adapter.

I thought I saw in another support thread that this is the adapter that used in-house at Looking Glass Factory, but I might be misremembering. Is there a Mac HDMI adapter which has been tested/approved for use with Looking Glass?


Hi Jay,

Now that you’ve confirmed that HDMI works with another machine, I’m reasonably confident that this is an adapter problem rather than a defect with your Looking Glass, so we’ll work to get you sorted.

Regarding hubs: we typically use these, but I do believe we’ve also had success with the Apple multiport adapter. For what it’s worth, these USB-C devices don’t have the bandwidth to deliver both a USB 3.0 hub and a 60Hz display out at greater than 1080p, so in order to get the maximum refresh rate you either need to step up to a Thunderbolt adapter (expensive) or buy a cable that goes directly from USB-C to HDMI (no hub / internal electronics).

Most of our Mac work in-house uses machines with native HDMI so it’s good to get some feedback on this issue. I bought a popular USB-C / HDMI cable and will test it tomorrow to ascertain whether we can recommend it as a reliable option for people experiencing this issue.

For what it’s worth, I would expect one of the multiport hubs to reliably drive a Looking Glass at 30 Hz. Mac GPUs will probably bottleneck multiview rendering before screen refresh rate becomes perceptible, so this may not be an issue for you at this time.

I’ll do a little bit more research into the sorts of USB hubs that tend to work with the current generation of Macs and get back to you with more suggestions shortly.

Thanks for your patience!



Thanks for the info - I’ve ordered one of the adapters you linked to and it’ll be here Friday. I’ll retest after it arrives.

In the meantime, the Looking Glass is hooked up to our gaming PC and the kids’ minds are blown so mission accomplished!


Hey @jaygrieves! Nikki here from Looking Glass Factory. I just experienced this on my own Macbook Pro with a Looking Glass unit here in the lab and I thought we were running into the same issue. After a bit of troubleshooting, I realized that I had my displays extended and that my extended screen (running in the Looking Glass) was set with a black background and so I had assumed nothing was flashing in my Looking Glass when in fact it was a problem with the display orientation itself.

I doubt that it’s the same problem you’re running into to but I wanted to just mention it anyway. I wanted to make sure that you were running in Mirrored and not Extended when connecting the Looking Glass to your Macbook!


Hi Jay -

We did just confirm another Looking Glass that works with a PC but not with a Mac, where the same Mac subsequently worked perfectly with a different Looking Glass. Are you still experiencing this issue? If so, we should continue this conversation via email.

Sorry for the slow responses - hope your vacation went well. I did end up testing that cable out and it seemed to work fine, so I’m curious to hear if you had any success.



When my LG first arrived I tried it on my MacBook Pro 2017 using a SATECHI multi-port adapter that has HDMI. It does not work (was just green). Then I tried the Apple adapter and it worked. However, the machine does not have enough horsepower for the demo software, so I switch to a beefy PC with an NVIDIA GPU. Good luck!


I recently starting encountering this after swapping my unit back and forth between a few different MacBook Pros (15" w/ TouchBar (2016)), iPad Pro 3rd Gen 12.9", and a Windows PC.

The Looking Glass worked fine on the MacBook Pro with the Apple USB-C Digital AV adapter prior to attempting to swap between devices. It works fine on the Windows PC, but doesn’t appear on any Mac OS or iOS devices. I notice a bit of slowness immediately after plugging the device in (as if its attempt to enumerate the display), but the display fails to appear. The Mac display didn’t flicker or switch to black.

Some of the things I’ve tried to resolve the issue:

  • Rebooting the Mac
  • Swapping between ports
  • Trying 2 different USB-C dongle and USB-C -> HDMI adapters
  • Swapping out the HDMI cable
  • Forcing the dedicated GPU to run via GfxCardStatus
  • Resetting NVRAM
  • Resetting SMC
  • Rebooting into macOS safe mode

Strangely enough, the issue also reproduces on my work MacBook Pro 15.6", whereas before it didn’t, so it appears the issue is following the Looking Glass hardware on Mac OS only.

While I was poking around through some log files, I happened to notice the following line which looks relevant in /var/log/displaypolicy/displaypolicyd.PEG0:

u>2420402238 LinkUpdate: 4.0 event: Remove [1]
u>2420402317 NOTICE: Addr: 4.0 event: Remove [1] source: 0
u>2420402378 NOTICE: inject FB[3] change
u>2420588753 NOTICE: kIOFBNotifyOnlineChange 0x9 fb[ 3 ] -> offline
u>2867738715 NOTICE: accepted enter mode …
u>2942662059 NOTICE: accepted exit mode …
u>2942686848 NOTICE: accepted enter mode …
u>2943322008 NOTICE: kIOFBNotifyOnlineChange 0x1 fb[ 0 ] -> offline
u>2943774390 NOTICE: accepted exit mode …
u>2943775267 NOTICE: accepted enter mode …
u>2952065157 NOTICE: accepted exit mode …
u>2958485432 NOTICE: accepted enter mode …
u>2977549639 NOTICE: kIOFBNotifyOnlineChange 0x0 fb[ 0 ] -> online
u>2980027990 NOTICE: accepted exit mode …
u>2983227994 NOTICE: EDID read 4.0 failed: GPU failed the command for block 0
u>2986434809 NOTICE: EDID read 4.0 failed: GPU failed the command for block 0
u>2989633457 NOTICE: EDID read 4.0 failed: GPU failed the command for block 0
u>2992831921 NOTICE: EDID read 4.0 failed: GPU failed the command for block 0
u>2996280041 NOTICE: EDID read 4.0 failed: GPU failed the command for block 0
u>2999481661 NOTICE: EDID read 4.0 failed: GPU failed the command for block 0
u>3002934353 NOTICE: EDID read 4.0 failed: GPU failed the command for block 0
u>3002934454 WARNING: To errorQ addr 4.0 id 0:0 order no:0 fb 0 tx 2:2 dsp 4 WL 0 MS 0 undef 0 err 5:0:0:0:0
u>3021473924 NOTICE: accepted enter mode …
u>3021814433 NOTICE: kIOFBNotifyOnlineChange 0x1 fb[ 0 ] -> offline
u>3022276247 NOTICE: accepted exit mode …
u>3022276314 NOTICE: accepted enter mode …
u>3034753827 NOTICE: kIOFBNotifyOnlineChange 0x0 fb[ 0 ] -> online
u>3037237315 NOTICE: accepted exit mode …
u>3040452229 NOTICE: EDID read 2.0 failed: GPU failed the command for block 0
u>3043654007 NOTICE: EDID read 2.0 failed: GPU failed the command for block 0
u>3047109734 NOTICE: EDID read 2.0 failed: GPU failed the command for block 0
u>3050308452 NOTICE: EDID read 2.0 failed: GPU failed the command for block 0
u>3053758966 NOTICE: EDID read 2.0 failed: GPU failed the command for block 0
u>3056960326 NOTICE: EDID read 2.0 failed: GPU failed the command for block 0
u>3057214766 WARNING: To errorQ addr 2.0 id 0:0 order no:0 fb 0 tx 2:2 dsp 4 WL 0 MS 0 undef 0 err 5:0:0:0:100:

This sort of logging appears somewhat consistently whenever I plug and unplug the device from my Mac. Maybe the display EDID information was overwritten somehow?


Hello, my first post here and I’m disappointed. Looking Glass doesn’t work with new Macbook PRO. I have 13 inches top spec machine. I can get only pixelated lowe res picture… so I need to buy PC? Is kind of joke… You should think about it first before. Now I was read in the paper manual that tracking option works also only with PC…
This is not the right way. You should inform customers about it before. What about customer support? Do you work on it or no?


@legionaire45 Sorry to hear that you’re having this issue. We’ve seen a few reports of it and are looking into what the root cause might be.

I’m attaching the EDID dumped from my Looking Glass, s/n 1192; I used MonitorInfoView to do it. There was a slight change made to the EDID mid-production to disable an issue where a Looking Glass would identify it as an audio output device, so I’m not sure which side of that update your model is on, but if you’re planning on overriding the EDID it shouldn’t matter as the hardware is identical.

In that folder there’s also an EDID ripped from a Looking Glass prior to the change - if it turns out that one of those works and the other doesn’t, that would be a tremendously helpful piece of information to help us with debugging, but feel free to try either. Hopefully we can get this issue sorted soon!

Hi @Michal_Majchrowicz, sorry to hear you’re having issues with your Looking Glass. Do you see a 3D image, and can you confirm from System Preferences -> Displays that your display resolution output is 2560x1600?


Thank you for following up! I attempted to dump the EDID information for my unit using MonitorInfoView (and a few other tools…), but none of them are able to get as far as even detecting the unit.

While I was poking around on my windows machine, I happened to notice something which suggests that my hunch regarding EDID corruption is somewhat in the right ballpark. There’s a group for the device in the windows registry (Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\DISPLAY\Default_Monitor\GUID-ish-thing\Device Parameters), but the only entry key is an ominously named field titled “BAD_EDID” of type REG_BINARY, which contains a zero-length binary field.

On a whim, I created a new key titled “EDID” and set its value to the provided older-model EDID dump (my serial number is in the 900’s). That didn’t help, and the key was removed as soon as I yanked the display and plugged it back in. I encountered the same behavior with the newer EDID. macOS remained unconvinced.

I’m guessing the only reason I have a dead-display-walking in Windows is because the Nvidia drivers are doing their own weird thing with the EDID information (perhaps ignoring the header or checksum). The Nvidia display settings are reporting what looks to be a reasonable list of resolutions to choose from and report the model name as a Toshiba LKG display, so they’re clearly handling things somewhat differently from the standard Windows/macOS driver.