Thank you for the question OP, I am researching the same. I'm not finding in the documentation provided that RECORDING can continue in background. It only suggest that PLAYBACK can continue when an app moves to the background (inactive, paused, hidden lifecycle state). Although please let me know if I am missing it in this resource! (https://developer.apple.com/documentation/AVFoundation/configuring-your-app-for-media-playback) Based on the specific activities that the documentation says 3rd party iOS apps CAN do in the background, it excludes audio recording. This concurs with all the stackoverflow, reddit, etc. questions & experiences for iOS 14-ish and later that I've found... But I haven't found any actual Apple documentation that says "no, this is not possible for 3rd party apps". https://developer.apple.com/documentation/uikit/preparing-your-ui-to-run-in-the-background

I had this occur when a user clicked on 'Accept Invite' in the initial invitation, but was unable to login (either due to their own inability or a connection issue -- they were unable to describe exactly what they did or what happened). Their user disappeared from our team's 'users' list and i could not re-add them, because they already existed (though they were completely invisible). I asked them to send me the invite email, and I clicked on the 'Accept' link in it myself. The next page acknowledged that the invite link had expired, and had an 'OK' button. I clicked that, then I returned to the 'Users' list, refreshed, and her user account appeared. Is any of the above a sane or reasonable excuse for the user disappearing? No. But perhaps it reset some cached data or similar, or finalized a workflow that was broken when the user couldn't log in after accepting. Worth a try to resolve: Have the user try to click on the invite 'Accept' link again. Or open that link in an different browser. Or, get the link and visit it yourself.