I think I found a different solution to fix this (for now).
In this thread: Cannot unselect “streamed” packages in my library - Bug Reporting Hub / Miscellaneous - Microsoft Flight Simulator Forums I have found a fix for unwanted MSFS 2020 addons to be streamed into the sim. Guess what guys, since ever I removed all 2020 addons the sim can now go back to main menu without any trouble 
Sadly this is not an option for Xbox users either 