Audacity doesn't like my headphones?

Earlier today, headphones were working fine with Audacity. Later on, when i pressed play on a clip, i got an error message… something like can’t open device try changing audio host playback device and sample rate… after a little process of elimination it appears it won’t play when i have the output in audacity set to headphones… weird… and yes, headphones were selected in SOund preferences on the mac… did not check audio MIDI setup though…

Are they bluetooth headphones? Audacity is know to not play nicely with bluetooth headphones on Mac.
– Bill