I don’t think I’ve read of this here but I just ran into this.
If I open a project and work with it a bit, then close it out and go to open another one, the newer project loads correctly with all it’s correct tracks, etc… Perfect! However, when I hit ‘play’, the newer project disappears and the old one appears, and the audio playing is the older project. It’s like POOF! Vanished.
Oh, P.S. When I say ‘close it out’, I leave Cubase intact and running, and then do the drop down tab to find the new project by selecting ‘Open’, and then selecting the particular project.