Have you tried looking at Apple's troubleshooting suggestions? (Sorry I don't have any better suggestions at the moment, but this might be better than nothing.)So a weird issue.. I had beta 10 installed on my late 2013 iMac and had everything working, including Apple Watch unlock. I've now upgrade my phone to a new iphone12, and a start of that process, I had to unpair-repair watch with the phone.
I now can now longer activate Apple Watch to unlock the iMac, with an error message that its unable to contact watch and ensure its on your wrist and unlocked and your phone is unlocked
Any ideas?