I have recently bought a Z2 tablet and me and my wife has separate user accounts. It works like a charm...with one exception. I tried to install the Spotify app on her account as well. But it crashes directly at start-up. Spotyfy works well on my (main) user account. Other streeming apps like Netflix, YouTube works well on both accounts.
I tried installing Spotify on the second account after updating to version 4.4.4. So I dont know if it's related to the update.
