Apologies for putting this in the FR 945 forum. There doesn't seem to be a place for 920xt posts anymore...
In any event, my 920xt has learned a new trick over the last few weeks. When I navigate to an Activity Profile, the elevation shows correctly (~500 feet), but as soon as I hit Start, the elevation rapidly rises to ~65000 feet in about 6 seconds, and stays there.
When I end the activity, and try to start a new one, the elevation is back at expected level.
I've used compressed air to attempt to clear the barometric altimeter port.
I've reset the watch to defaults.
Any other ideas? Link to video below.
https://www.dropbox.com/s/d4o0moj4js87557/920xt%20Elevation.MOV?dl=0