Help Fluids not recognizing holes in terrains

[Softscale]

I've got a regular Unity terrain in my game world, with a Terrain Collider and Obi Collider, and fluid collision works fine in most places - but in one part, there is a hole cut in the terrain for a cave mesh. I've noticed that fluids won't cross the threshold where the hole in the terrain was painted, and any fluids created inside the cave (below where the terrain would be) are immediately forced upward/outward to the surface of the terrain.

I did find a workaround that works for my use case (disable the ObiCollider on the terrain when in the cave) but I'm wondering if there is a better solution for being below a terrain. Thanks.