After Samsung Galaxy Watch 42mm with One UI update, I can't install Samsung health update on the watch. Watch just disconnects when update is installing. I have Samsung Galaxy S9 (One UI) & Samsung Galaxy Watch 42mm (One UI).
Same here on Galasy S8.
Reset is not fixing the problem but I've discovered that you can install apps / watch faces through Galaxy Store app from watch itself.
Same here with a 46mm Galaxy Watch. The comments in the german Samsung store has around 900 posts with this Problem. Samsung Hotline didnt know what to do.... Hello Samsung?