My watch on a link bracelet started locking constantly right around the release of OS2. I assumed it was a bug in the update.
The culprit turned out to be that it's getting cooler outside. My wrist was shrinking a bit in the cooler, drier air, and a previously unworn long sleeve cuff was also sneaking underneath the watch, breaking the connection.
I have since switched back to the sport band and no longer have lock issues.
Looks like the look no bracelet is a summer only option for me.