Your show's Blubrry directory listing has picked up your most recent episode. If the other two platforms (TuneIn and Stitcher) are still behind, you'll need to contact support for those services and ask them to refresh your listing. Most of these services have algorithms that are used to keep your listings up to date. When they notice a feed has stopped publishing new episodes, they may stop checking those feeds altogether, or they may check those feeds with less regularity.
You can contact TuneIn here:
https://help.tunein.com/contactYou'll have to e-mail Stitcher: content@stitcher.com