Turn off "delete from bucket when deleted in WordPress"
By default, deleting a media item in WordPress also removes its files from your bucket, which keeps the bucket tidy. To keep them, open Offloft → Settings → Uploads & sync and turn off Delete from the cloud when deleted in the Media Library. The setting saves automatically.
With it off, deleted media items leave their files in your bucket until you remove them yourself in your provider's dashboard. You'd pay your provider to keep them.
With it on, if a file can't be removed, Offloft raises an issue and keeps trying.