I've seen similar questions posted in the x-plane forum, and didn't see a resolution. I use a bluetooth connector to my hearing aids that act just like a bluetooth headset. On longer flights it seems like it almost always seems to lose connection. I still get other plugin sounds like better Pushback. I get all system sounds.
So then I try to put a wired headset on, and I still do not get X-Plane plane sounds, just system and plug-in sounds.
This happens with default Cessna, Zibo 737, FlightFactor 767, ToLiss Airbus A319 - so it's not aircraft specific.
Using Windows 10 (latest updates), X-Plane 11.11.
For some reason X-Plane does not behave like a 'normal' windows application when audio gets restored. And switching the default audio does nothing with X-Plane.
All other apps and browsers have much more flexibility and resilience.