It seems you have cleared/deleted the old “Learn” category, but now everything goes to “Certification Exams” sub category even though the posts are not related to certification exams.
It is even impossible (currently) to create a new post under “MongoDB University” category anymore. There is simply no button to do that.
Under the main category, there is only “New Event” button which requires some permission as if it is a MUG topic.
We have updated the settings and users should now be able to create a post that is related to the University learning under the MongoDB University main category.
Changes in the forum itself may have this kind of undesired result. A side note to moderators would be nice as it is easy to miss out on these effects.