I have been using Forerunner 45 for over a year now and have recorded 157 running activities.
During an activity two weeks ago, my watch stopped tracking it and oddly froze, buttons were not reacting to anything (watch just showed the frozen time of day). After I have finished my run, I have restarted it and there was no activity remembered, but things felt normal until my next run. While this one ended up being tracked correctly throughout the whole run, saving took forever and ultimately, forced me to restart it. Again, no activity could be found from it. I tried a total reset of settings + deleting activities from the device (never done that) before my next run. This one was again tracked well throughout its length, saving worked, but the result screen only showed me following:
Weirdly enough, the watch remembers I have ran the correct kilometres in a summary, but when I click the activity in the history, it shows this screen once again. When I try to sync, no activity is synced with my phone. This is the state my watch are in right now. I did another two runs like that, no change.
I tried to look on my watch through file browser on my desktop, there are no activities stored on the device (there's few empty folders and few files). Generic health data seems to be read well by the watch, but it does not seem to be synced to my phone and I suspect the watch also looses that info after switching off and on. I also had an event during a weekend, during which the watch just froze without doing anything at the time. Noticed like half an hour later that the time was off on them.
Does anyone here has a similar experience and could help me somehow before I try to return it? 
