Hey just finished chimney JQ during the JQ event. Got no medal/achievement for finishing it just a normal box/hat reward. As far as I know chimney counts toward jump quest medals? This is my first time completing it so it's not that I have done it before. IGN: MonRayer Completed it on another character on that account though: sealstorydog.
I'm going to guess that you did the chimney jump quest on a different character than the one you used to complete the other ones. I'm sorry to break it to you, but the medals are cumulative per character. Notice how the medals are named "completed x number of jump quests" instead of "completed forest of patience 1" etc. Happened to me as well - I did Ludi Tower on a mule by mistake and had to wait for another chance on my main character.