My HoloPlay Preview window in the device is offset to the side - which side depends on whether I have the screen set to the left of my main screen (offset to the left) or the right side of my main screen (offset to the right). Builds work perfectly, this is just the Preview in Unity.
Holoplay SDK 1.0, Unity 2018.2.12, Windows 10. In other forum posts there was some options screen under the Holoplay menu in Unity, mine only has the “Toggle Preview” option, no Position or Presets buttons.
I found an undocumented (as far as I can tell) solution - you can now right-click in the Project, choose Create->HoloPlay->ManualPreviewSettings. And that object lets you manually choose the screen offset (I needed -2022, -68 to make mine full screen centered).