Alex,
We had all manner of curious similar gremlins with our Raymarine pilot. They started when it was about 4 years old and were completely unpredictable which made them both dangerous and annoying. I think John Franklin had similar problems with his. He solved his by replacing the memory chips. We eventually sent ours back to Raymarine and they re-programmed it. Ours has been OK since then but we are keeping our fingers crossed!

The problems we encountered were:
1. Suddenly and unpredictably disengaging
2. Misinterpreting heading data from the compasswhich caused it to lurch off course. Often it would think that our heading would be up to 180 degrees out!

My guess is you have a corrupt software issue.

Simon

We purchased a Raymarine autopilot (used), and spent the season last year calibrating and recalibrating it. When engaged it steers our boat in sinus curves with ever increasing amplitude and increasing violence. Very scary.

Raymarine has not responded....