Spotify won't play one of my local files playlists

[dvojitev]

So I've uploaded a few of my local files to my Spotify account. I always put them into a playlist as that's the only way to sync it on my phone, and it's always worked perfectly, except for one - it acts like a completely normal playlist and the songs even "play" - there's just no actual sound. They're all mp3 files, I have Spotify Premium, my Firewall isn't blocking Spotify and it all even works when I play the songs from the desktop version, so I really don't know what could possibly be the problem...