Downloaded playlists songs set as not downloaded

[lsoml]

Device

Motorola Moto G3

Operating System

Android 6.0

My Question or Issue

I have a SD card set as Internal Storage, and I download my playlists to it. At some point, the playlists are shown as not downloaded (the download switch appears as off).

It's occured several times, and I used to just turn it back on and download all the playlists again. But I just noticed that when I do this, it downloads to the phone actual internal storage, not the SD Card, and the memory space on the SD Card is not cleared (it remains the same size as before the playlists vanish).

It seems like it loses the reference, or something and I have to delete the app, free the cache and data, and do all the process again.

As said, it's occured lots of times, even when my SD Card was set as Portable.