Project "lost" or invisible after opening mastering plugin

I worked on a project for some hours yesterday, and after opening a mastering window to adjust the sound and finish it, all I see now is the mastering "pop up" window.

I can't see Logic Pro window or none of the recorded tracks at all, but when i hit the "space" button on the keyboard, it starts playing in the background.

If I try to close the mastering pop up window, the project is closed as well. Trying to re-open it, same thing is happening. It only opens with the popup window. I have tried to restart the Mac as well.

I am very grateful for any tip or hint to get my project back and to finish it completely. (Needless to say, it was many hours of work, and I would hate to loose it)

Here is a picture of the screen that appears after I open the project, and this is the only thing I see. If I close this window, the project closes too.