I had a scary event just now.
I renamed a large folder (60GB, 150K files). I got a message it would take some time.
So :I sat and waited for the operation to complete. In the meantime, I saw the new folder appear, with some content. Then the content was gone. Then all my files appeared in the deleted files section and only after about 15 minutes, everything completed OK.
I won't lie, I was somewhat scared. I suggest the web UI provide some progress indication for this and similar long operations.