Disappearing footprint?

Hi there,

I am trying to "liberate" some world items. One of them is a rock from Cats&Dogs (2809D). After making it buy-able I saw that I cannot place it without the moveobjects cheat. The footprint was there and it was red. I remember someone here said that this may happen if the object is partially below the grid. This rock sits in the ground, so I moved up the meshes in Blender. Now I can place the rock without the cheat but the footprint disappeared. I did not check if it still blocks sims from walking through it, but I can place a carpet underneath the rock, so I think it does not.
How can I raise the object to be able to place it without cheats, while keeping its footprint?

What I did in Sims4Studio:

• choose "Create 3D mesh"
• change name, description, price, tags (remove the tick from World Object, add tick for Rocks), add a swatch
• change DevCategoryFlags to xxx80
• export all meshes, adjust them in Blender, and import them back
• click "Adjust Footprint" button

In Blender:

• select object (I tried both Object and Edit modes, and I tried Select All by pressing A or selecting only the mesh by clicking on it. Saw no difference)
  
• press G Z .61 to raise the mesh and save the file
• repeat for all meshes (lod0, lod1, shadow lod0 and shadow lod1)

Any ideas?