I am able to easily get Flip fluid interaction with Geometry made in Houdini, but imported OBJ will not interact. What could cause this?

The object has holes in it and will not form a closed surface for collision.

Drop down a vdbfrompolygon, after your File load of the .obj file, to inspect what the collision surface actually looks like.

Enivob
The object has holes in it and will not form a closed surface for collision.

Drop down a vdbfrompolygon, after your File load of the .obj file, to inspect what the collision surface actually looks like.

Thanks so much Enivob! A Fuse and Clean sop combo did the trick.