GW2 No sound *MULTIPLAYER ONLY* PC

Hi I've been Google'ing for a while can't seem to figure this out. I posted on this on Reddit here and now here. Thanks for your time!

This began today after a recent upgrade to Windows 10. Did not have this problem in Windows 7. The sound is perfect in single player but when joining a friend's game or they join mine, I lose all sound (including any other programs that are open) After exiting the game or returning to single player, sound is back to normal.

PC, Windows 10 (up to date), Bluetooth Headset. In the volume mixer (image below) you can see there is sound going to the headset (ie, the sound meter is moving) but nothing getting to the headphones. Tried windowed and full screen, no difference. and set sound to stereo (not surround)

edit: Uninstalled and reinstalled, did not help