Audio Stops on a specific Project after 1 second

Hey, so I created a new project, everything worked fine, but suddenly the sound stopped. The different mixer channels show sound, but the master channel doesn't. Also, the little eq on the top of the screen doesn't show anything. The master channel is not muted (At least the green light is on) and all the mixer channels are plugged into the master. When i try to close Fl and reopen the Project, I hear sound for llike 1 second and then it stops as described.

I'd be thankful if anyone could help me. Im on FL20