I am just connecting up my 5500. I have three problems that I can't understand.

1) the height shown on the display is 43,000 ft. I'm pretty sure that I'm not that far up! other systems connected to the pitot are reading fine.
2) the system is connected to an old 3500 with crossbow ADAHRS. I can not adjust the pitch. I can get the readout of what it is set to next to the joystick. and it reads 0.0. however it will not adjust at all.
3) the connection to the GPS is very inconsistent. I have a Garmin G5 and a Avadyn 440 connected. They either both work fine or both sources read as being at the north pole. Both give an error message when off line, that message disappears but sometimes the map knows where I am other times its the north pole.

Could you advise me what to try.
Ta