@Mark Thanks for your reply. From that I gleaned that the AP disconnect is not a feature of the aircraft so perhaps something might be wrong on my end.

I did a long testflight during which I unplugged my yoke and throttle quadrant and that seemed to cure the AP disconnect. After reconnecting the AP disconnected again after a while.

I checked the yoke sensivity setting in MSFS and noticed there was a "reactivity" setting I have never touched before. It showed 100 so I changed that to 98, on a hunch that this might filter out these spikes.

I did a long test flight with this setting and did not have a AP disconnect. The funny thing is, when I set it back to 100 I also did not have these AP disconnects anymore.

When I later checked for spikes using VKB Joytester I noticed that the yoke was indeed sending spikes once in a while, very short bursts but off the scale.
These did not lead to AP disconnects since I already touched the reactivity setting in MSFS.

Even after a very, very long flight the AP disconnect did not return except once when I changed GPS instruments on the tablet during a flight.

Perhaps the original value of the reactivity setting was not set properly in MSFS internally so setting it to 98 and then back to 100 reset something in MSFS.
Sorry for the long reply but hopefully someone else with a similar issue might benefit from this.

@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.