I'm trying to flag a post, but I cannot

I selected “Something Else,” and typed the reason why in the resulting explanation box, but I cannot seem to post it. All I get over the “Submit” button is a red circle with a slash, and nothing happens when I click. What gives?

I tested just now on this very post (without hitting enter), and I can’t reproduce your problem. Or maybe I didn’t try hard enough.

Likely a mod had already removed the post while you were trying to flag it. You need to refresh the thread for it to vanish.