Hi guys, fixed with help from Dan and a JF ticket. I checked all the button mapping for the Honeycomb Bravo. Nothing for fuel cutoff, but I did find this in my mixture button mapping:
DECREASE_MIXTURE 1 - set to number 28
DECREASE_MIXTURE 2 - set to number 33
I had been using number 28 for Set Starter 1 (Hold) and button 32 for starter 2. Clearly button 28 hit both the starter and mixture decrease, then when engine number 2 started, I rocked the switch back to number 33 and mixture again decreased. I saw no conflicts when I mapped this, but I think that was on another mapping profile. I had no idea about these bindings until I searched the Controls for 'Mixture'. I've cleared the mixture button mapping and now have a dedicated Baron Pro profile. So happy to have the Baron back in the sky! Thanks for all your replies and help. Happy New Year everyone!