Downloaded songs getting deleted after turning on phone

[MDiaz13]

Plan

Premium

Country

Chile

Device

Samsung Galaxy S9+

Operating System

Android Pie

My Question or Issue

Hey guys need some help here. This issue is new for me and it has become really annoying cause it deletes every single song I've downloaded in my library. I always turn off the phone before going to sleep and, when i wake up and check it, all the songs are gone, and oddly, the storage changes to the device instead of the SD card. Any help would be appreciated!