It’s been a few months since I did this workflow and there has been a new version of Mocha Pro since then, so I’m assuming the fix is something in a setting somewhere.
I’m in AE working at 16bit Rec709, apply Mocha Pro, track my shot, export a clean plate, clean it up in PS, back in Mocha I do an insert. In Mocha the inserted patch is dark. If I import the clean plate in AE and set Mocha to use an AE layer as the source the patch is too light. What’s going on here?