I want to say both, but definitely while on a cellular connection. I'll need to double check on the wi-fi.
I will also try using Spotify on my phone and iPad (at the same time) and see if it device specific issue or it effects both ( account or network issue)
I use t-mobile, which has some deal in which streaming music doesn't count towards data usage. I am wondering if there is some funkiness on whitelisting/proxying of domains / urls that breaks the ad server content for some reason...
Iphone 6 / 128Gb (model MG572LL/A) iOS - 8.3 Free space - 74Gb Spotify version - 220.127.116.114
I took some screenshots of the broken ads if that is helpful. If so, I can upload them somewhere and provide a link.
Also - just to see if it was a phone specific thing, I tried my account on an older iphone 4 / iOS 7.1.2 / 12.4gb available / same spotify 18.104.22.1684 on the same network and it worked as intended. So it seems the issue is specific to my iphone 6.
So I upgraded and the ad still doesn't load. However the behavior has changed. After not loading the ad for about 3 seconds, it then goes to a music track (unsure if it counts as if I clicked on the ad and get 30 min ad free or not)
So, at least I don't have an app lock-up anymore. Still weird though... (As it doesn't happen on any of my other devices)