Thank you for your answer!
I checked your points, did the firmware reset and plug the original proc as you suggested.
The firmware reset, aven the load of older versions does not change this behaviour.
The pin 6 looks fine, and when I plug the old processor, the arp works as it always did.
So I’m still a bit lost.
I tried to compare with polysix’s tubbutec kit and I can’t see much a difference.