I had 3 projects in the projects menu. I did not notice the state of this list at the start.
I created a new, 4th project. Next time I went into the project menu, project 1 was my active/current project but project 2 had a checkmark as if it were the active project (is this the intent?). I selected project 1 again and same thing. I switched to project 2 which now became project 1 and the checkmark disappeared completely. So now the checkmark isn't there any longer…