It actually did correct itself (during the activity that started ‘3 years ago’) once I got a satellite lock in the open, the bummer was my activity showed in GC on the wrong date and then it lasted like 1200 days. Funny, sort of…
Eventually I got the fit file edited ok to crop the footpod / bad date data out and loaded it into GC ok.
I actually had 3 faulty 310xts that couldn’t hold the time when they were turned off. That essentially made them useless for indoor training because the date and time was always wrong (unless you went outside, got a satellite fix, and then turned it to indoor mode). After the 3rd one I returned Garmin finally sent me a good one!