Local Files completely don't work

[careful]

I am completely frustrated because absolutely none of my local files are working on my iPod or Samsung Note 4. They're all completely greyed out on the plaaylists, the local files folder doesn't work in either of the apps, and renaming them or redirecting the source isn't working either. I've had this problem for months, and months, and each time it's a different answer. Once, it was that there's a bug that iOS can't play songs with any punctuation. Okay, fine, I'll delete all the punctuation. They worked for a little bit, then became greyed out again. I uploaded songs directly from a CD. Still don't work. I download a random remix from Soundcloud for free. Doesn't work. I did a digital download from an album I got in the mail. Still doesn't work. NONE of my local files work at all in offline mode - they work fine on the desktop, but then not on my devices. 

I have the latest version. I have the latest iOS, the latest Android system - I have uninstalled, reinstalled everything. Nothing works. I disabled my firewall. Nope. I googled this for about two hours, nothing. What exactly is the problem? I'm getting ready to just quit spotify because now the problem has escalated from being one or three of my local files to none working at all. 

[ahnayk]

Also same problem. I have greyed out files on my iPhone and followed all the steps ad naseum. Really frustrated.