I cannot open any notebook within the Wolfram cloud from the desktop.

I have Programming Lab Standard V11.3.0 Standard license, i. e. including the local desktop application. Running on Windows 10 Pro 64bit.

When I start the desktop, login with my Wolfram-ID and then try to open a notebook from menu "File.Open from Cloud" I can see all my notebooks in the cloud, but if I choose one for open, I get an error-popup:

"https://www.wolframcloud.com/objects/wernergg/190427 Drei Hunde.nb" was not found. Please check to make sure you are logged in as the correct user and have permissions to access this object.

Hence I cannot use the desktop at all. I think, this strange behaviour came with version 11.3. Before that I was regularily working within the desktop.

If I use the web interface lab.wolframcloud.com (from the Microsoft Edge browser) everything works as usual (Let aside that it is horribly slow).