Where does Category list comes from?
As an experiment that worked. I found a rar file of 897 songs that was created for Ultrastar Deluxe and then created a new folder under songs, extracted the songs there. When I open MLK there is the songs and more categories.
I don't see any tags on Category.
Hey! Sorry for the late answer. Yes, it works that way; you can then go to the Options menu, activate Tabs and sort by Folders.
(https://i.imgur.com/AjtB1F6.png)