Hosting Audio Unit MIDI plugin support on iOS

Is anyone successfully hosting MIDI Audio Unit plugins on iOS?

I’m hosting instrument and audio effect Audio Unit plugins on iOS with JUCE with no problems, except for MIDI plugins.
No MIDI output comes from these plugins.

I went into and starting hacking it up.
I’m having zero luck with setting the MIDI output callback, kAudioUnitProperty_MIDIOutputCallback.

When I use AudioUnitSetProperty() it seems to set, no change from the JUCE code. The error code is 0, all good.
When I use AudioUnitGetProperty() to retrieve the callback I get an error (-10879).
No callback seems to get set.

This function is called before the AudioUnitInitialize().

I’m targeting the iOS 12