Playback issue when additional folder inside

Volumio 3 playback Issues?
I’m a relatively new Volumio user. I can play only files within a folder, but when album folder contains additional embedded folder, like covers, art etc), the playback is not working at all. The workaround is to delete cover/art or any other folder from my album folder. Wired.
When I can play tracks, I can play whichever I want in the folder on my android phone, but on PC I have to play one by one only. I can’t pick up the track from the list to play.

I’m playing the tracks from my Synology NAS using DLNA option, because your guide how to add this NAS to the library or NAS discovery is not working.