Not easily reproducible but I've seen it several times over the last weeks, and it just happened again.
add container, switch to Favorites tab
click on a project, Continue => grey window!
reload page ==> now on selected project
This only happens once (the first time the app is used).
Note: If I do Back, then I get back to the dialog and the container I had selected is added to the list...
At that point I can finish and my view is created...