Landscape collision from both sides

I’ve built a cave into my landscape, and am using the underside of the landscape for some of the cave roof. The only problem is that my pawn moves right through the landscape from the inside, even though the landscape blocks it from the other side.

Is there a way to make collision work from both sides? If not, my next step would be to create my own collision with blocking volumes. Might there be a better way?

Thanks!