Hi all,I just filled the bug report 39600781, regarding 'aumi' (kAudioUnitType_MIDIProcessor) audio units and AVAudioEngine. In short: in iOS, when attaching 'aumi' audio units to an AVAudioEngine, the AVAudioEngine will never call their renderBlock / internalRenderBlock, rendering them (pun 😝) useless.I write this post because I know that 'aumi' audio units in iOS are undocumented, thus some quirks are to be expected 🙂. But since some developers are already implementing them (I am beta testing their apps), I think it is important to raise awareness that 'aumi' audio units do not work with hosts that use AVAudioEngine. Note that hosts using AUGraph work, because they need to explicitly call the renderBlock method of their audio units. Yet since AUGraph is going to be deprecated... well, if "aumis" are to be officially introduced in the next iOS version, it is important to raise awareness about this particular issue. That's all. Thanks for reading 😉.