Hey,
I have spent some time EQing two guitar tracks, they are soloed.
Once I unsoloed each one to hear them in the mix, one of the channels went dead. The only way to get it going again was to stop and start playback. Sometimes doing it just once can do it, other times it takes a few goes.
Bypassing and deactivating the inserts on the problematic channel when it was dead did not make a difference, so the 3rd party plugin was not at fault.
Thanks