Logic Pro Sync with Soundbrenner

Hope you can help me, as I am getting nowhere with either apple support or soundbrenner support. I am trying to connect my iPhone 8plus to my macbook pro, both running latest versions of system software, in order to sync it with Logic Pro x, so that I can get Logic Pro to send a midi metronome signal to a soundbrenner app on the phone to run their soundbrenner pulse wearable metronome.

I am able to do all that, but it seems that the simple act of connecting my iPhone, enabling it through the audio midi setup utility, and setting sync preferences through Logic's preferences midi menu, then precludes me from recording through anything other than inputs 1 and 2. My mac is connected to an apollo x8p, so I have 8 channels of input available. As soon as I disconnect the phone, all the inputs are available in logic.

Any suggestions would be appreciated. I will also see if I can find a soundbrenner user community. Thanks!