I'm facing issues with user management in TIA V16 and WinCC Unified V16. I added two users in "Security settings -> Users and roles". When I click on the "Synchronize button" and log in as the UMC Admin (configured in WinCC Unified Configuration application), I keep getting an error like on the screenshot.

I also cannot log in when opening the UMC web service - there I keep getting error "The validation of the parameter 'service' failed.". All services required for WinCC are set according to this FAQ: https://support.industry.siemens.com/cs/us/en/view/109773589

Any suggestions? I'm stuck in it and cannot move any further.... My goal is to add an user to the panel and start using the Edge functionalities, but I cannot log into IEM without any user added.