I have the same issue. Nothing of the iCloud features works on my mac after an update to macOS Big Sur (11.0.1) I tried to turn on/off wi-fi, bluetooth, tried to forget and re-pair my Macbook and iPhone but it didn't help. Features those doesn't work for me: Universal clipboard; Unlock with Apple Watch; Handoff; iPhone in the list of networks and connection to family iCloud devices. Also when I try to re-enable Watch unlock settings says "Your Mac was unable to communicate with your Apple Watch. Make sure your Apple Watch is unlocked, on your wrist and powered on." and the feature doesn't turns on.