I have a Spotify Connect enabled Ultimate Ears MEGABLAST speaker over which I typically listen to Spotify at home using an iPhone X. I however stumbled over an annoying issue…
Quite some songs fail to be played back via Spotify Connect, like for example Guns N‘Roses - Live and Let Die, only exhibiting a short crackling at the beginning before audio via Spotify Connect automatically gets muted.
I now found out that this happens if MEGABLAST and iPhone have previously been connected through Bluetooth inside the Spotify app. I found a workaround by setting the iOS system-level audio output from MEGABLAST/Bluetooth to the internal speakers. Afterwards all songs play nicely through Spotify Connect/WiFi again.
It is really weird that Bluetooth somehow „interferes“ with Spotify Connect on the iPhone and that not all songs are affected by the playback issue. I first thought it was a speaker related issue but the found workaround made me think otherwise. It might very well be a problem with the Spotify app.