I am going absolutely insane trying to figure this out. I've searched through the forums, but I have not been able to find anyone who is trying to get a CC character into Mixamo.
At present, I've tried all options for export from CC, and the character does not import properly.
I read in one forum response that you could use 3DX to export the character so it is compatible with Mixamo, but my "Convert to Non-Standard" button is grayed out when I attempt this.

Does anyone have a workflow or tutorial for CC -> Mixamo?

Thank you.