OVROverlay (Underlay) world-UI drifts with head movement

Hi everyone, 

I recently started working with OVROverlays to achieve a better visual quality of my UI in VR. My scene setup is as follows: I have a world-space display object with a Quad child that uses an OVROverlay in Underlay mode. The Quad has a fixed world pose (not parented to the camera), MeshRenderer disabled, and I assign the same RenderTexture to both eyes.

When I move my head sideways, the UI on the underlay appears to “swim” or drift relative to the 3D display, instead of staying fixed. Interestingly, this only happens when I build. This might be because I’m feeding a mono texture to both eyes, so there’s no stereo disparity. But wouldn't I see that in the editor?

Has anyone experienced this? Any idea or fix is very welcome. Thanks beforehand!

Laura