Did it by chance merge and not refresh the UI? Try opening the user that should have been deleted’s admin page in a another tab.
I recall this happening to be occasionally when I merged accounts, and reloading showed that the account in question was merged, the page just never redirected to reflect that.
Unfortunately no - both accounts are still active.
I see a disclaimer of ‘users cannot be deleted if they have posts’…this guy has 4k posts created…
Any advise there?