For an existing app, I upgraded to the Atlas UI, which works fine. I followed this article: https://atlas.mendix.com/p/upgradetheme/7881299347898769
Now I would like to use the Web Modeler as well, but the Edit button gives only the option to edit in the Desktop Modeler. I added the settings.json file, replaced the NavigationLayouts module. Even tried to use the theme folder from a working Web Modeler app I created from scratch. But doesn't seem to work.
Probably I'm missing a setting somewhere. Hope anybody could help.