X8 strange issue, telemetry vs USB

I am having a strange (well, to me) problem on an X8 running 3.1.2 on APM 2.5.

After initial config, X8 flies fine. (All parameters stock). If I connect via radio, the HUD shows a 25 degree pitch (when level), and the X8 is unflyable. If I disconnect the radio (and check back via USB), HUD is level again and X8 flies fine. This happens even though the copter has not moved when connecting/disconnecting.

Any idea what might be going on? I’ve recalibrated the accels 1/2 dozen time, via terminal, via radio, via usb, no difference.
Could I have run into max memory limits?

Could I have run into max memory limits?

I doubt it. it uses the same amount of memory to run on USB as radio.

I have an APM X8 sitting here and it is working fine.

You can always go back to a previous version as well.

It is probably some issue on the frame itself. Can you post a log and we might see what is going on.

Well, can’t really make any sense out of this. Dataflash logs don’t appear to show anything. A similar thing that happened more recently: Copter sitting still, unarmed, unconnected except via radio, and HUD telemetry suddenly shows 25 degree plus roll and stays there, even though the copter is perfectly still and level.
Nothing short of disconnecting battery and re-powering will “right” the HUD … Meanwhile I completed a 20 minute flight in 20mph+ wind gusts so I doubt the frame is an issue …

I’ll try to provide logs if this happens again, unless you think that a tlog could help now …