This came up in issue 6944 but we haven't figured out why it happens yet.
Try opening a terminal to the project folder (which has a file named Podfile in it) and run the command: pod install
That might report some more details about the problem.
The issue issue 6944 is marked as Closed but there is no working solution there. What should we do then?
Old projects still can be run on my side but none of a new one, which is pretty critical. Thanks!