Landscape Hole Casts Shadow On Static Geo

Cutting a hole in the landscape and then lighting it with a stationary light results in the geo behind the hole acting as if the invisible geo of the hole was casting a shadow on it. To clarify, no light passes through the hole to light the interior of the “cave” in this case.

Is there some way to make a hole in a landscape that light will properly bake through? Do I have to use a dynamic light for this? Any help is appreciated. This seems like a pretty big oversight in consistent lighting.

Same problem