Looking at the code, the only thing that could cause that behavior in the Caravan is if either the Elevator Trim, or Autopilot Actuators circuit breakers are pulled. Any hardware that is possibly assigning these electrical circuits might interfere, but it's unlikely this would happen without you knowing what you assigned in 3rd party binding software. This would also be possible with the Analog Caravan, and it's also possible that any circuit breaker failures have carried over to the Caravan Professional, since I used the same namespace for the failures. Other than that, I would be left suspecting something on the hardware level, since I haven't received any reports of this before. I am happy to help here, but it might also be worth contacting Just Flight support, as they deal with many aircraft, not just mine, and may have seen this behavior before. Sorry that you've been dealing with this since the Analog Caravan! Hopefully we can get it fixed for you quickly!