There was a problem when trying to transfer a project to the watch.
This didn’t solve my problem:
1) Hold down the Watch power button(s) until it says rebooting
Restart your computer as well.
Wait a full minute for all WiFi to be fully synced.
Make sure Developer Options is on and debugging is enabled
Launch GWS and enter your IP address if you don’t have it already
Observe your watch carefully, having it on a factory installed watch face helps
click on Run on Device select your watch and run
Watch your Watch and when it says RSA Encryption tap the check mark
It should run on watch.
2) Updated Distributor Certificate
UPD: Problem with GalaxyWatchStudio appeared after updating WatchFaceStudio
I have the opportunity to test GalaxyWatchStudio on another computer. On another machine with my author’s and distributor’s certificate, everything works fine.