X-plane 11.26, TBM 1.0.8.
Did a short flight today. Went up to a cruise altitude of FL180. When I started descent I noticed that the altitude on the PFD was stuck at 18000 and not going down. Standby altimeter was working fine. I recycled pitot heats, checked the circuit breakers, nothing seemed out of order. Tried aux static, didn't help. Airspeed readout was fine all along.
Managed to land, powered down, checked the payload page to make sure I didn't forget to take anything off, checked the maintenance page and saw there are absolutely no malfunctions anywhere. There are also no random failures active. I then turned the aircraft back on and saw that it was still showing 18000. A screenshot is attached, as well as the x-plane log file and the TBM flight log file.
Thanks a lot for your support so far!