And how can it be fixed? Can you change folder permissions (if it's even possible) without rooting? My MP3 are all in a (default, I suppose) folder in the SD named "media". It worked more or less fine in my old phone, a Galaxy S2. For a few files I had to use iTag to fix some of the tags in the past, but now that I've moved to a S4, it's not working. Most of the files were already tagged correctly, but any new ones I've added since that have wrong tags can't be edited, either in PlayerPro or with iTag. In Player Pro it gives me a message "failed to edit tag" or something, but in iTag it seems that it's working and it's saved, but it's not.
I use PlayerPro as my main player.