iPhone will not register as an "Offline Device"

[smacman]

Recently I've been having a problem with my iPhone where every few days it would tell me that I already have 3 offline devices and remove all saved music.

I have

a) signed out of Spotify on all of my devices and,

b) reset Offline Devices from the web interface.

The trouble now is, when I log back in on my iPhone (or any other iOS device), although I can sync offline music initially, the device does not show up as an Offline Device on the web interface. At the moment I have synced offline music to my iPhone and iPad however the Offline Devices section shows : "You don't have any offline devices". 

Launching the Desktop version of Spotify on any of my computers however does take up one of the 3 spots, and after launching on my Desktop, Laptop, and Media Center PC, all 3 Offline devices are used up (even though I am not syncing any music for offline use). This of course causes the iOS devices to purge all Offline music again (even though they were set up first).

Really pulling my hair out with this. Any ideas?