I got it worked out. I removed all the masking, collapsed all the layers and started over. There were too many masking settings on too many sub-layers, or something. Weird that the masks showed up correctly in the editor though.
It can be a workflow PITA when things don't work in the same way you expect them in other software just by nesting masks, a little more thought needs to go into simplifying the requirements as much as possible but simplifying pays in the end!
I really like the look of this new animation Nina, looking forward to seeing it.