The last two times I plugged my Forerunner 15 into the computer nothing happened. It says "nothing to sync" even though there are several runs saved on my device. The last time, it just blipped and spontaneously synced after many attempts to plug and re-plug. I've read about this problem before, but the difference is, in my case, there's no error message--it just doesn't "see" anything to sync (until it seems to feel like it). I've tried resetting, but no luck. Does anyone else have this problem or know how to solve it?
It sounds like you are having physical connection issues since it worked after re-plugging it a few times. If this continues, you might want to contact support.