In the attached file there is a Part container with a body inside. The cube inside the body is visible. When I delete the outer Part container I say "no" to the question if I want to delete the contents too. That operation leaves Body with its contents.
However, the Body is invisible, whether I toggle it or not. The same holds for all features if the body is more complicated. The only solution is to save and reload the file.
Did I miss something?