@Vero
I uninstalled a few apps that could manipulate files, but it didn't help. Regarding your other question, when I navigate to ~/Alfred/, I can actually see the Alfred preferences package, but the Alfred app doesn't allow me to set it as a sync folder.
After checking all of that, I created a new user and installed Alfred 5 again. I then created a new folder ~/Alfred/ and set it as the sync location. Now, it seems to work. Afterwards, I copied the updated Alfred.alfredpreferences package (the one I'm using with Gdrive) to ~/Alfred/, and it worked as well. But when I install Gdrive and try to set the sync location, I'm prompted again with the same error message.
Returning to my previous user, I tried again to set ~/Alfred/ as the sync location, but it didn't work. However, when from this non-temporary user, I set the ~/Alfred/ folder of the temporary user as the sync location, it now works.
The other interesting thing is that I have another Mac mini (Intel) in which I'm experiencing the same issue. However, on my MacBook Air M1, everything works nicely.
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