I have 2 alternate watchfaces (The Spitfire & Star Trek Face ) and a couple of 3rd party apps including my own home written Enduro app, and everything runs smoothly.
Did you try switching off completely your watch ? How did you do your update ? phone or PC ? Might want to try and connect it to your PC and Garmin Express.
Only widgets and watchfaces did not work, apps all worked. Deleting and reinstall did not help - but turning the watch off and on again solved my problem! Thank you