I had the same problem on my Edge 1040 solar...
and today on my 1050... the altitude is completeley inaccurate, see those two courses:
https://connect.garmin.com/modern/activity/16848077478
with Edge 1050 9.11
and the same with Fenix 7
https://connect.garmin.com/modern/activity/16848076789
the Fenix is correct, 388 meters, the Edge 201 meters.
is an old issue with the barometric sensor... tried hard reset, clean altitude port, reistall maps... no way