Your post is not the first one showing strange box
behaviour when client_id is used:
as chunker can't rename the file it cleans temporary uploads - this is expected. I would assume it does not use thrash
- which would be right thing to do. It would require looking into source code to check, Either way your test with rclone move
confirms what the issue is. Your client_id can not rename files. Why? I have no idea:)