Unions with negative parts sometimes break

So I’m making a tunnel and a few holes. I saved myself a lot of time using negative parts and unions. But when I went in-game, the parts where I’m supposed to fall into and hide are collidable and won’t let me in. Is it a problem with the negative parts or the union?

Set the CollisionFidelity of the union to PreciseConvexDecomposition and see if that works.