A folder (which I believe I was the owner of) which had many sub-folders & files has disappeared from my Box account.
I have checked with the other people who it was shared with & it has disappeared off theirs as well.
It happened when the person who owned the overarching box account made me an co-admin/owner.
I put my phone in aeroplane mode so I could get a screenshot of the folder before it synced & disappeared off there as well (which it did when I connected back to wifi)