@Mark Thanks for your reply. From that I gleaned that the AP disconnect is not a feature so thinking that perhaps there was something on my end I did a few test flights.

During a flight I unplugged my yoke and throttle quadrant and that seemed to cure the AP disconnect. After reconnecting the AP disconnected again after a while.
When running VKB Joytester I noticed that once in a while my yoke is sending a sudden spike which might be interpreted as a violent control movement. That probably causes the AP to disconnect. When I do that deliberately it does so.
The issue seems to have been solved when I changed the reactivity of both axes of the yoke from 100 to 98, and then back to 100. I never touched this setting before so perhaps the original value did not filter these spikes at all. If 100 does not work I might lower it a bit but sofar it seems to have solved the issue.

@Thor_999 said in Buxton/Peak Forest Extension:

I've just bought the Buxton/Peak Forest extension. When i selected a quickdrive route from Tunstead Quarry to Leicester, there is a problem with the wagons that have been placed in the sidings at Tunstead. They block the tunnel mouth so that you cannot leave the sidings where you start this quickdrive journey.

Sounds like what I saw and mentioned up thread about the same starting point. I think you can delete the offending wagons via the editor as a workaround.