Pretty bizarre issue. I popped in that same code and successfully replicated the issue. I then removed the calls to my_add_term, reset my permalinks (not sure if this helped or not but worth mentioning that I did it), added an item, reloaded, and they all showed up in heirarchy as expected.
In the calls to my_add_term, you’re passing $postID but that isn’t defined, so I’m guessing that’s where the issue is coming from. Bottom line, you don’t need to define Print and Digital as your base categories with every single page load, so that code can reasonably be removed. Let me know if this fixes it for you!
Cheers~