10.10.4 and H9 Control have a code-level BT issue, watching the console log I can see the complaint from OS X when H9 Control attempts to connect. Eventide people, would you like me to post the logs here, or email them to support? I emailed with Jerome last September, but every subsequent release of H9 control has yet to solve this issue.

You mean this error, "H9 Control[3366]: Failed to connect (mPasskeyDisplay) outlet from (IOBluetoothDevicePairViewController) to (IOBluetoothPasskeyDisplay): missing setter or instance variable?"  

Unfortunately, that error has been happening inside the compiled code of the Cocoa class IOBluetoothDeviceSelectorController since Yosemite.  There's nothing we can do about that.  I made a post about this on Apple's developer forums, but I never heard anything back about it.  But I also don't think that it's the cause of any connectivity issues as many people have been able to connect to their H9s via Bluetooth on Yosemite without any problems.