Landscape holes have collision if the mip level of the landscape is changed from 0 to 1.
1. Open Editor (any project).
2. Create new landscape.
3. Create new material.
4. In material, set blend mode to masked.
5. Create Landscape Visibility Mask node, plug into "opacity mask".
6. Apply, save, close material.
7. Select landscape and set material/hole material in details pane to new material. Change landscape mip level to 1 in details pane.
8. Paint a hole on landscape by going to landscape mode>sculpt>visibility then LMB on landscape.
9. Place a static mesh over the landscape hole and set simulate physics to true.
10. Press simulate.
Head over to the existing Questions & Answers thread and let us know what's up.