I simply moved the whole GSX folder directly in the "normal" Community folder, started MSFS again and that worked. Many times tested : no problems anymore since then.
Don't ever do that, and I suggest everybody reading this to NOT follow this advice, which will result in being cut out from updates, since the updater will only update files in the real Addon Manager, not in the Community folder, since it's assumed the program is LINKED there, as it should be.
Where, exactly, is your Community folder located ? There are two ways of having the Community folder moved in a separate way, one is an hack and it's wrong, another one is the official method, which works flawlessly.
1) WRONG METHOD
This comes JUST the Community folder on a different place, and creates a Symbolic link to it in the original place, for example here:
%LOCALAPPDATA%\Packages\Microsoft.FlightSimulator_8wekyb3d8bbwe\LocalCache\Packages\Community
There are several reasons why this method is wrong. First, is not the official one, and there's no reason wanting to use it when the official one works perfectly fine. Second, it causes addons "linked" there to be "links to a link", which might have side effects. And third, is not even achieving the biggest space saving, because you are only moving out the Community folder, while leaving about 180GB of "Official" on the Windows boot drive. And lastly, you RISK losing the whole Community folder when entering and exiting from a Public Beta.
2) CORRECT METHOD
Moving out BOTH the Official and Community folders ( referred by Microsoft as "Content" ) to a new place, and edit this new location in the UserCfg.OPT file. This method has none of the issues of the first one, because it's the officially supported method, it results in both the Official and Community folders to be "real" folders (eventually containing links), it saves an extra 180GB on the Windows drive, and there's no risk of having the Community folder being wiped out when entering/existing from Public Betas.
The ONLY "difficult" think, it requires editing the last line of the UserCfg.OPT file, which is located here:
%LOCALAPPDATA%\Packages\Microsoft.FlightSimulator_8wekyb3d8bbwe\LocalCache\UserCfg.OPT ( MS Store version )
%APPDATA%\Microsoft Flight Simulator\UserCfg.OPT ( Steamversion )
Changing the LAST line to look like this:
InstalledPackagesPath "E:\MSFS"
This is my case: I moved both the Official and Community folder into a new folder named "MSFS", which will look like this:
E:\MSFS\Official
E:\MSFS\Community
And edited the UserCfg.OPT to match that. If you do it correctly, MSFS won't even know something changed. Just be sure the path is enclosed in double quotes.
Now, the final check is: if your Community folder will contains Links ( normal for all FSDT installers AND if you use the Addon Linker ), the drive you are using for the complete Content
must be formatted in NTFS, this because other filesystems like FAT32 or ExFat, don't support Symbolic Links.