I am having the same issue.
I have to associate posts with the category to show up.
For instance, I to to POSTS | CATEGORIES:
– Type in name
– Associate a parent
– Click on a user group
– Click “Add New Category”
– It shows up in the list of categories.
– I refresh the page and it is gone.
– If I go into Post and create a new post I can see the Category.
The thing is, I cannot do anything else with the category until there is a posting associated with it.