Device: iMac (20-inch, Mid 2007)
Operating System: OSX 10.11.6
I use the desktop free version downloaded from the spotify site. Originally it wasn't even playing ads. We realized it started when we noticed the music had stopped. Now it happens all the time. I have heard some ads. It's now stuck on Filtr (ad), whatever that is. I've also seen it stuck on Boston Pizza (ad) which we have in the area.
Btw I get no error message. I simply see the screen showing as though the song is playing, but the progress bar is sitting at the beginning. When this first started I couldn't get it to start playing at all and had to close and restart spotify. Now I'm able to hit the pause button which turns to a play button. I hit that and the ad plays.
I read that Spotify was having issues with 3rd party applications skipping the ads. It seems more likely that they have issues with development and quality assurance.