Apple Watch no longer unlocking MacBook Pro or Mac Studio

My AppleWatch Ultra has stopped unlocking my MacBookPro, as well as the MacStudio.

Tried several different options (and several times…) but nothing seems to work.

This is very annoying - I used to be able to just open my MBP in the office and the watch would unlock.

Now I have to be careful about who is standing close to me as I type the password.

A couple of years ago there was the same problem which then appears to have gone - is it back ?

[Re-Titled by Moderator]

Original Title: watch not unlocking MBP+