Can't Paint Foliage on Hierarchical Instanced Static Meshes?

I don’t understand why this might be happening. I’ve followed a tutorial by CodeLikeMe on how to create a procedural mesh tool using a spline using HISM. For some reason though, I can’t paint foliage on the meshes. It’s like they just don’t exist according to the tool.

I’ve got some procedural building assets in the same scene from a Marketplace pack that use HISM and I CAN paint on them so something specific about my procedural tool is making it incompatible with the foliage painter.

Here’s my code:

Construction Script:

PlaceInstanceMesh Function:

For anyone else with this issue, ClockworkOcean gave me the solution on my answer hub page before Epic froze it… If you change the Object type under the collision properties to “World Static” it fixes the issue.