QR codes not updating

[sjando]

I've been experimenting with the samples and also doing my own testing with a Unity-based project using the new XR_MSFTX_scene_marker extension in the preview runtime to detect QR codes.

I'm finding that XRSceneMarkerMSFT objects don't ever seem to update within an XR session. That is, the lastSeenTime and size properties remain constant even if the QR code remains in view (in which case I would expect lastSeenTime to always be recent) and its size is changing over time (in which case I would expect the size property to reflect the changes). This appears to be the case whether the code is first spotted during the session or whether it was an existing code that existed before the session and stuck around.

This can be verified by running the QR sample, resizing a virtual QR code on a screen and observing that the visualization does not change (other than location). When dropping back to the HoloLens shell the system QR code visualization (green outline) immediately becomes responsive to the size changes of the same QR code. Relaunch the sample and observe that the 'most recent' size is now reflected in the visualization but it will not change again (other than location).

Is this intended behaviour or perhaps a bug in the runtime?