Can't believe they're not coming back to you! Or have they just said it will be fixed in an update?
Yep, know that it won't work after a restart to get in the first time - I mean, if I actually get it working, it loses the connection again after a restart!
To get it working - untick 'use your apple watch' in security, then on Mac log out of messages and log in, log out of facetime and log back in, restart Mac, phone and watch, then tick 'use your apple watch' in security, after about 5-10 mins it should work.
Who wants to do that every time though!!!!
I have a 21.5" Mac at work - works always, every time, no issues. I have a MacBook - works always, every time, no issues.
I wish I knew the secret as to why my 27" Mac at home does this!!!