iOS/iPadOS permission requests not being shown [resolved]
There is a problem with iOS permissions relating to app lockdown modes - specifically if the device is running in Guided Access, Single App Mode, or Autonomous Single App Mode. When the initial permission request is made (i.e. Bluetooth, camera, microphone, etc), that request is not shown on screen. At that point, even if you exit the lockdown mode and re-attempt triggering the permission, it will not be shown.
Resolved. Updating to iPadOS 15.4 appears to resolve the issue.
Previously, we replicated the issue on other third-party apps so this issue was an Apple bug.
Besides updating, the only workaround we've found is to delete and reinstall the app, then trigger the permission request prior to placing the app into any of the lockdown modes mentioned. Once the permission has been granted, the device can then be locked down and the camera, microphone, etc. will continue to work as expected.