Here you can check if your Mecenat card is updated with the public transport discount symbols. You can search for your personnummer to check your status.
(note - unfortunately the function below is only available in Swedish)
If you can see the discount symbol when searching below, but do not see it on your Mecenat card? If so your phone needs to clear the cache for the app. Logging out and back in again usually sovles this, otherwise delete the app and download again. If it still is not showing contact customer service (here) with a picture of the card attached.