I've been using the Vivoactive for a month now and have experienced several times when the device has booted: on sync, when loading an activity, when making a step goal. No repeatable pattern, just random. These have been mostly just annoying, but it was maddening when it happened at 8 km into a 1/2 marathon when I was on pace for a PR, then got all messed up trying to figure out what went wrong and where I was at on the fly.
Last week I updated from firmware 2.8 to 2.9 and that seemed to work, but this morning it just randomly booted while it should have been doing nothing other than showing time. As usual, it cleared the step count and assumes that I have been asleep all that time.
It's very disappointing to have this problem and makes the device of limited value if it's not going to do the job it is supposed to when I need it most.
Do the developers have any idea what is causing this problem and if there is a fix?