When the new version 1.18 UI designer started to crash from time to time but it works. Now with this new 1.18.2 version mu UI designer does not work at all. In the window where the design is supposed to be is some long error text with some .JS issue. When I compile my application it works with no issue.
Application that has a problem with the UI is a converted application from .NET7 so as I am in the research phase it is not important. I built a new .NET8 application and there is no problem. So consider this as a trivial problem.