Two things: Galaxy Wearable shows wrong "time since last full charge". Eg I've just fully charged my watch five minutes ago and it shows 2 hrs 5 mins ago. Way out.
And...you can no longer select complications and shortcuts on your watch using the Wearable app. It just shows the setting for "none". You can, of course, still use your watch to do this, but it's easier on the phone app and this bug is proving very frustrating for watch face developers who are getting complains from customers while Google/Samsung seem in no rush at all to fix this.
Seems the One UI 5 Wear OS 4.0 is particularly buggy.
No solution sorry, but commenting to say I've got the same issue. I have found some watch faces still allow complications to be edited from phone, so wondering if there is an issue with some developers API
Just to let you know....I've spoken to a couple of watchface developers who say they're having many problems with Galaxy Watch One UI 5 update...they seem to blame Google's Wear OS 4 for the glitches, although Samsung must have OKed the software before release.
Anyway...I reported it to Samsung who seemed to know about the bugs but said their internal developers would be made aware of the problems.
Hopefully, they sort it soon.