I'm not familiar with the midimux / studiomux app in Windows, but maybe there is a MIDI feedback loop occurring? Are there any free MIDI CC apps for iOS you could reproduce this with (maybe the issue is not iOS but the MIDI relaying in studiomux?)
Oracle just sends MIDI to whatever port you chose, it can't / won't hog that port up or prevent it's use from other apps, so I'm unsure what is going on.
Anyone else on Windows?