I've brought up the issue a couple times before. A while back there was an update to the DB that altered how the coding works a little bit. Now, you need at least one empty line and a space between the ">" and the quoted text. You used to do it like this:
But now, you need to do this:
It should be noted that the answer preview will still show the old way as being correct, so double-check your answers once you post them until you get used to the new coding.