Today - on a track activity, when saving the 2nd screen of perceived effort (smiley faces) once I hit OK on the default face, my watch crashed and restarted.
The activity seems to have uploaded to garmin connect and looks fine on connect - but it's not on my watch anymore (as if the run never happened).
I tried chatting with customer support - which said "we're sorry - the activity is gone" - he wouldn't acknowledge the fact it did in fact upload - but the watch deleted it. So posting here in case this is not a currently known issue.