This happened on tex.sx, but I assume the underlying software is universal. There is no point in displaying that post, there's nothing more to do with it than deleting. Trying to add a "not an answer" flag returns an error message. I'm not sure who deleted that post, I think it was the poster themselves, which might be the source of the problem. Or perhaps the fact that there are two kinds of flags on the post? The problem doesn't seem to be a glitch, it's been there for three hours since the post was deleted.