Can't click anything

Hello all, 

I can't seem to be able to click anything in AE interface, as if there is a pop-up window preventing me to do so. I can use shortcuts and use the very top toolbar (file, edit, etc.). If I select "Quit" it won't close the program and I will have to force quit.  If I click on "show all windows" it will show just one window, the one with the main interface. 

This is happening only with a specific project, if I open another one, I can navigate and use the interface with no problems. 

I'm on an iMac 27/inch, Late 2013 with 10.15.5 OSx