Some artists do not create an albums sub folder

[paulg]

Most of the artists on my server are grouped within the artists folder with the following sub folders.

Albums
Items
Date
Genre

Some however show the albums at the top level of the artists folder and the only sub folder is Items. The albums are tagged with a date and genre and so can't figure out what causes it. It doesn't prevent my playing the music but I just find it curious as to why.

I have attached a couple of screen shots to show what I mean.