Hi @clem.renault,
This sounds like an issue that we have seen that is specific to Amazon Drive (no other services have exhibited this behavior). It has to do with Amazon’s auto-purging of their cloud trash, which they do after 30 days.
Take a look at this post/thread for more details: Mysterious unknown files/folders under root Amazon Drive folder
This is something we’ve tried to tweak our implementation for, but the issue is ultimately on Amazon’s side, unfortunately.