Folder Sorting TV series, why 2 groups?

Why are all TV series where I have more than one season stored being grouped together and sorted alphabetically.
Then after that comes all the Series where I only have one season stored. It does not matter if there is a seasonal subfolder structure behind or not.

Sorting order:

24 (3 seasons)
Castle (2 season)
Zorro (2 seasons)
Alpha (1 episode)
Beta (5 episodes season 4)

etc etc

Simple things like sorting do not work correct. The app is unfit at the time.