Unity3D AssetBundle prefab with missing material

I have a project where I create an AssetBundle and load an assembly from a specified resource bundle. This prefab consists of an empty one, with one child that contains the mesh, filter mesh, collider, and material. When I download this collection, there is no material. However, if I remove the empty parent so the prefab only consists of one object with the previously listed components, the prefab has everything expected.

Any idea why this might be happening and how I can fix it?