This is something of a strange one and something that’s been bugging me for a while.
When I connect bluetooth headphones to my Mac, regular system audio output switches to them (music playback, sound effects, etc.), but not VoiceOver.
To get VoiceOver output through the headphones I typically open the VoiceOver Utility. Nothing else. I don’t need to change anything. Just opening the VO Utility is all that it takes.
This behavior has been seen with a number of different headphones.
I am assuming that there must simply be a checkbox somewhere that I have missed, but I can’t find it.
So, could somebody please help and point me in the direction of whatever I am missing. Thanks.
VoiceOver and Bluetooth
Try setting VoiceOver's sound output device to system default in VoiceOver Utility under the sound category. That should cause VoiceOver to mirror changes in the system audio. If you're still having issues, it's probably a bug in either the OS or VoiceOver.
When this has occurred, I've found toggling VoiceOver with CMD-F5 resolves it.