iPhone Jitsi Meet app loses both mic and audio when re-entering a room

We are using meet.jit.si for telemedicine. When the nurse contacts the patient using an iOS device and steps them through the conversation process, the audio works just fine. But when patient leaves the Jitsi room and then returns to meet with the physician, there is no audio in either direction. Changing the volume settings has no effect. The problem is always and only solved by exiting the app, killing it (“swiping it off”) and restarting.

This problem has been present for at least a few months, preceding the last app update.