Reply To: Understanding the scene collections and heirarcy
Don’t worry, it’s not that the Outliner is perfect, there are quirks, such is the Blender way. One convenient thing is that the “eye” icon is for hiding in the viewport:
So when you hit Alt + H to un-hide objects, things that have the icon turned off will pop again into view. But the monitor icon is for disable in the viewport, so it not only hide things, it disables them:
So if you have the monitor icon set to off, the objects that are this way, when you hit Alt + H to bring things back into view, the ones that have the monitor icon disabled wont come back into view, because they are disabled altogether.
Also if your end goal is to show or hide the head or body while you are working on other pieces, you can turn this logic inside out and not focus on hiding them, rather isolate the piece you want to work with. You can do that with Local View:
Hot Key is Numpad slash. So if you want to work on a foot and everything is getting in the way, instead of hiding everything else, just select the foot and isolate it to local view.