Logic Pro has had a problem with the MG3 Hex tracker Audio Unit since day one and there are other posts about it. In my experience, you are better off using standalone MG3 and feeding it into Logic.
I haven’t been able to apply Logic’s surround capabilities to feed 8 audio channels into MG3 Hex. If anybody can figure it out, please advise!
We’ve been experimenting with a AUv3 version of MG3 which can open the 6 channels of the audio interface directly in the AUv3 plugin. I actually submitted this to TestFlight a few days ago, but it seems to be stuck in Apples review still.