I‘ve got the same issue. I checked the miniCOCKPIT website for new updates for the miniFCU und miniEFIS but couldn’t find any. The firmware is some weeks old.
Maybe miniCOCKPIT needs to update the firmware etc. first so the A350 is able to communicate with the miniFCU/ miniEFIS.
I had the Problem several times while flying to Frankfurt (EDDF).
It seems, that the FMS is calculating every 5 seconds a new route…
The problem occurs on other routes too.
While changing the sim rate to 4x all inputs to the aircraft were frozen completely after few minutes of flying. Neither i was able to deactivate the sim rate.
During the final approach, I deactivated the autopilot. The alarm started ringing. Instead of going off by itself after a few seconds, the alarm kept ringing until after landing. Even the master caution button did not help to deactivate the alarm.