I am running macOS 10.12.6 on a Mid 2010 MacBook Pro. I can connect to my television (via HDMI) and my headphones (via Bluetooth) just fine. Video is sent to the TV correctly.
However, no matter what audio device I select the audio always comes out of the internal speakers. It lets me select whatever device I want in sound preferences, tells me it's selected, tells me the TV doesn't have audio controls... then sends the sound to the internal speakers anyway. I have rebooted twice. All of this worked fine yesterday and I'm not sure what could have changed.
I'm at a loss for how to fix this. Error messages I can Google but I don't know what to do about a computer flat-out lying to me.