Mocha Import & Reference Frame

I’m working on a set of jobs where I’m using timeline fx for color, and for practical reasons the import is not a source file conform but a flat render out of Premiere that I re-slice with scene detect. That part all works well.

I tried doing some of the masks in Mocha instead of gMask Tracer to compare tracking performance. The data import works well. But I’m running into a problem where the masks seem to be mismatched by timecode.

It works fine if I apply the Mocha OFX plugin on the timeline FX, export files and import those. But I’d rather use the standalone app, open the same flatpass render, set the Mocha clip range, track, save masks into a file and import. In theory the the timecode of the file in Mocha and the file in Flame should be the same, so I might be overlooking something.

Alternatively I was hoping there would be something like set reference frame, similar to what Motion Vectors have. Once you import a gMask, if you could just go to the first frame and say, treat this as your reference frame? There is a textbox at the bottom but it’s disabled in that use case.