I've been trying to find a way to get some of my local files to sync from my desktop to my iPhone, and I've been encountering some strange issues.
I initially was just attempting to add two mp3 files from my personal music into Spotify. When I put them into a playlist and marked it for offline sync, the playlist would appear on my iPhone, but the songs would not show up when I entered the playlist on my iPhone. Underneath the playlist title, it says "2 songs" with a gray arrow next to it, so it apparently detects that the songs are there but doesn't show them in the playlist. While synced with my computer, I attempted to play one of the songs and then switch devices to see if it would play on my phone, but it just gave me a message saying "Song not downloaded."
Next, I attempted loading in a local file of a song that I knew was already on Spotify to see if that would work. Downloaded the playlist for offline sync, no issues, worked fine.
Then finally, I tried downloading a different local file from my old iTunes library that I knew wasn't on Spotify. This song appeared to download just fine, but when I tried switching devices to play the song on my phone, it comes up with the "Song Unavailable" message. I thought it was weird, because it was a different message than when I attempted to download my own mp3 files that were not from iTunes.
So it looks like I'm able to sync certain local files, if they are already on Spotify, but not others. Would there be some kind of issue with the local files themselves? And if so, what steps would I need to take to "fix" those files so that they will download properly?