I started a hike as normal, saved it when I was done--but there's no record of any activity. Unlike the last time this happened it did count the calories and steps. At the time I finished I was in an area with cell service that at best could be described as marginal--could it perhaps have messed up somehow because of that? It definitely did not sync even to my phone until I was home even though my phone was right there when I told it to save my hike.
I'm also having some trouble with the heart rate monitor--relying on the sensor in the watch produced some obviously bad data in some situations and I got the heart rate strap--but even that messed up yesterday. I saw some numbers below 60 during an admittedly easy stretch. I found the watch unreliable in those conditions (chilly, but ok so long as I kept going; not worth digging stuff out of my pack) but why would the chest strap be affected--it's electrical, not blood flow based.
(I wasn't wearing a shirt at the time, temps were probably in the low 60s but without the recording I don't know, humidity was low, basically zero wind, the sun had set but I had enough moon that I wasn't using a light.)