Does Rescan not work?

Hello and greets from Belgium,

I am a newbie. So actually I am testing Volumio. I am interested to put some music on my SD-Card. Therefore I have made a folder INTERNAL in de directory Volumio_data dyn/data/INTERNAL/ After a reboot Volumio also found some albums. However not all. Via ls –l I have checked if the albums are present. And they are. Does someone know why Volumio cannot find all of my albums? Also not after a rescan.
Thanks a lot for your help.