I found the bug. I’ll do a proper writeup in this space soon, but the gist is they do latency testing as part of the timewarp headpose prediction; they do this by drawing a rectangle of varying color in the upper right (out of user view).

Our code doesn’t do this, because it’s only present in some of the D3D-based example code (TinyWorld), not in the OpenGL-based documentation PDF.

I bet the other demo app code has some surprises lurking, as well.

More thorough writeup in this place, soon.