I just noticed this problem too when I upgrade my phone to iOS 15.3. All the usdz file I have on my phone now only display in "Object" mode but not "AR" mode. This is really big regression, please let us know when the issue is addressed. Just a random guess, maybe somehow AR Quicklook doesn't have permission to access the camera anymore after some conventions changed with the OS update?

I'm trying to do the same thing to add an inputBus to an AU v3 instrument in order to get a Sidechain dropdown menu in Logic. I'm also having trouble, did anyone every figure out how to do this? I was able to reproduce the same behavior as user "jfjs". As far as I can tell this is the same boilerplate as in the AU effects example posted by user "NB System".