I just tried it. Setting AUDIO CC OUT to EXT means the knobs don’t do anything in audio tracks, like @disco was describing in another thread.
Also, I get no audio from my main outs, if I set AUDIO CC OUT to EXT, and THEN power cycle, just like @julien1 described.
Setting it to INT (I always keep mine on INT) gives me audio out on the next power cycle.
Nice find. I wonder if this is an initialisation problem (internal snapshot not getting to track machines) rather than an audio problem as such. Doesn’t explain why it randomly cut out for @jennygirl tho.
Edit: I’ve got an OTmk2, one of the very first ones, but it’s had a replacement board because the encoders were jumpy so it’s a bit of a mishmash of hardware versions in there probably 
Running 1.30C.