Pioneer DEH-X7850BT Spotify Input Not Working

[rp30]

This morning I had to reset my iPhone and reinstall everything (including Spotify) from a backup.  Everything seems to be working well, except for Spotify via the Spotify input on my Pioneer DEH-X7850BT car stereo.  When you try to use Spotify via this input, the screen on the sterer stays on "Start Up App" even though the app opens automatically the the input is selected.  Subequently, no audio can be heard via this input, but can be heard via the iPod, App and BT Audio inputs.  It was working fine prior to this morning's restoration.  So far I have tried the following:

•  Uninstalling and reinstalling the Spotify app on the iPhone
• Clearing the BT memory on the stereo
• Deleting the stereo from the iPhone and deleting the iPhone from the stereo, then repairing
• Resetting the stereo

None of the above has worked, and I am now concluding that it is the iPhone that is causing the problem given it only happened after the restoration. Any assistance greatly appreciated.