After updating the firmware to version 15.20 I have with my Garmin fenix 5x plus similar problems with altimeter as described HERE. Has anyone noticed a similar problem or I am alone?
Go to www8.garmin.com/.../download_details.jsp download the file. Unzip it and copy the gupdate.gcd file that you find in the System_Backdate_v14.00 folder.
Connect your device to the computer and paste gupdate.gcd inside the GARMIN folder of the watch .. it is impossible that there is not
Just wanted to add my elevation issues with 15.20 with Fenix 5 Plus: Elevations during activities seem to be OK but when not in an activity I am getting random wild spikes and dips in elevations. Never had this problem before 15.20. The average elevation where I am is 350 feet or so. No mountains or deep sea dives!

