It is possible that certain categories may not be visible in your learners App; there may be two reasons:
1. There is no training course in the category: when a category is created but does not contain any training (yet), this category is not displayed in the App. The category can be visible only after you integrated training course(s) into it.
2. The learner is enrolled in no training course of the category: when a learner has no access to any training course from a category, this category is not displayed in the App. A category can be visible, only if the learner has access to at least one training course.