Audio issue with all libraries on Windows: "doesn't match broadcast shape"

I think I’m having the same problem: Midi working, audio isn't

This is for a single participant. The experiment is working fine on most people’s computers…

Is there a simple workaround for him that doesn’t involve changing the code? Can I get him to switch the audio output of his computer to a mono output somehow? The error message seems to mention his bluetooth headphones… could these be the issue somehow?