Watch: Connection lost - check bluetooth

[Rathje]

Hi
I have a Nothing 1 phone with Android 15. I have an OnePlus Watch 3 with Android 14 and WearOS 5, but even though it used to connect fine the last couple of months it has failed to with the message connection lost - check your bluetooth. All my other watch apps works fine using bluetooth.
I have un- and reinstalled both on phone and on watch so locusmap is on phone and locusmap for watch is on phone and watch. In settings I have allowed add-ons and there are no battery restrictions.
Why can't I get it to work, please?
Best regards
Lars