I wanted to create surface models from the attached label map (P2AbtinSegmentation.mha) using ModelMaker. I had to click apply twice, because only half of the created models appeared after the first run. (BTW, this is another bug.) Then I wanted to delete the models. After I deleted all, a gray vertebra model stayed in the 3D view. But there were no model nodes in the scene anymore. It looks like an orphan actor in the renderer.

It disappears after closing the scene.