I believe I have the same issues as in this post, but unfortunately it’s closed.
I have been trying to change some text in this post (and another one which I cannot link to due to new user restrictions), but I get the same error (“You cannot change a poll after the first 5 minutes.”). Please note that I am not editing the poll at all; all I am trying to do is turn some text in the Schedule section of these posts into a link. It doesn’t matter whether the poll is open or closed.