Finally found the solution. Turns out the autopilot dumped the memory, and so had to be completely recalibrated. Dockside calibration, then compass calibration at sea with a couple of circles to get deviation.
The solution came from the raymarine help line while sitting on the boat.
Rebooting didn't give me any changes, so I eventually called the help line. After about 15 minutes they had it figured out and so all is now good.
Thanks for everyones efforts.