I fly the Baron a lot. I have noticed that, somewhere along the update cycle, something changed in the reaction of the prop/mixture controls.
I have a single throttle axis that controls both throttles. They seem to track together nicely. I use the key bindings for mixture and prop. Although they are bound as a single axis, they do not move in unison. When adjusting either control using the key bind, I have to use the mouse on each individual lever to fine tune and get the engines in sync.
eg: pull rpm back and one lever will move further than the other. Mixture the same. End result, asymmetric thrust.
I spend most of my time hand flying the Baron and balanced thrust is paramount. Do not use rudder trim unless you lose an engine. The sim aircraft is also VERY sensitive to power setting. If you find yourself rolling left or right with the engine controls balanced the likely cause is either too much throttle or not enough. At the right prop/mp setting the Baron will hold heading, hands off, nicely.
Don’t muck about with trim, other than pitch obviously, but once you have the engines in sync, adjust power to find that sweet spot where she tracks rail straight.