My Observer has begun acting strangely with regard to altitude and baro pressure.
If for example I set the altitude at 600ft, my present altitude, without me changing my location, it begins to ascend by itself. By the end of the day I’ve put on 400-500 ft.
The same holds true for Baro pressure. It ascends but not in line with the current pressure.

Does anyone have any reason for this?
I am taking off for a trip on Sunday with some climbing involved and would greatly appreciate a quick response as I would love to have this problem solved prior to leaving.

Thanks,
kwr