Hi, Johnny. I figured out the issue here, and it's not iOS 8.4 specific. The problem is that Sunrizer doesn't react well to two MIDI streams at once. Make sure you either turn off "MIDI Designer Initiated Virtual MIDI" MIDI Out under Connections, OR uncheck Sunrizer under "Hardware and Virtual Destinations".
Also, ensure that Background Audio is enabled in Sunrizer if you're not using Audiobus or IAA.
Let me know if that solves your issue.
Thanks,
Clif