That’s odd - do you get any errors about missing components when it loads?
Here’s the definition:
It might just be a tolerance setting? it looks in your image like the 2 sides of the cushion are somehow not being treated as separate.
also, I saw another recent related project from MIT by some of the same people, where they actually use Kangaroo for the simulation:
https://trackr-media.tangiblemedia.org/publishedmedia/Papers/642-OTIzM/Published/PDF