I'm trying to make a patch of grass by populating a surface with a mesh I have created in Blender and imported in Godot. When I try to use MultiMeshInstance in this way, I get an error message: "Mesh source is invalid (not a MeshInstance)". This is clearly because, apparently, models are imported as Spatial nodes with MeshInstance containing the actual mesh as a child node and a Spatial node can't be be used as a source mesh in MultiMeshInstance.
Is there any way around this problem?