Hi Gabriele Bevilacqua

These issues are very difficult to diagnose, but as a solution would it be possible to copy your single TM to a local drive when using it and copying it back to OneDrive when you are finished?
I think that would resolve the syncing issues.
As for comparing OneDrive and Dropbox, in my personal experience syncing is much faster with Dropbox.
From what I heard, Dropbox only copies the part of the file that needs to be updated while OneDrive has to copy the entire file again (I am not sure how true this is though but you can find articles on the internet claiming this). So, this is why you may have not noticed on Dropbox. 

Hi Gabriele Bevilacqua

These issues are very difficult to diagnose, but as a solution would it be possible to copy your single TM to a local drive when using it and copying it back to OneDrive when you are finished?
I think that would resolve the syncing issues.
As for comparing OneDrive and Dropbox, in my personal experience syncing is much faster with Dropbox.
From what I heard, Dropbox only copies the part of the file that needs to be updated while OneDrive has to copy the entire file again (I am not sure how true this is though but you can find articles on the internet claiming this). So, this is why you may have not noticed on Dropbox.