It occurred twice. Once it it jumped back 8 1/2 hrs resulting it jumping back a day (It later self corrected to the correct time and date). It happened again today and it jumped back 2 days 18 hours.
There is a no way to manually set the date and when the watch jumps between days and hours it screws up the activity tracking.
I had the same problem but was able to fix it by resetting the watch then going outside, hitting the run option and standing in an open area until it picked up a GPS signal. The first time took about 1 minute but thereafter it was only a few seconds. Haven't had the time/date issue any more.
If you turn the watch off time pauses and you need to reset it with gps. Perhaps that's it?
Out of curiosity I just turned my 235 off for five minutes. When I turned it on, it immediately displayed the correct time, well before it established the bluetooth connection to my phone and I was indoors well away from windows so GPS likely wasn't involved.
Yes... It works: after a PC sync, my Forerunner 235 lost it's date (showed a day before than real) and hour (more or less 12 hrs before).
I tried all day... sync-ing to the computer, to the phone, etc. I even "reset" the watch to factory settings... Nothing worked. Reviewed configuration everywhere (it's not possible to adjust date manually !!!), etc. Nothing... At last I found this forum thread... I could not beeive it, but I took my arm out of the window... wait until GPS was OK... start a short run of 10 sec, which I discard... and OOOps !!! Time and date were perfectly correct !!! Thus... it's true: date and time are received from the GPS !!! I could not beleive it... Thank you from Barcelona !!!
If people are coming from other vendors, or even from the Garmin vivoactive, many set the time using the mobile.
After having a FR15, when I first got the vivoactive, I was confused that GPS DIDN'T set the time! And was presently surprised when the 230 again used GPS :)
