What do you mean the root object is a panel or a widget? The two are completely different components. Panel draws widgets. Widget is drawn by a parent panel. If there is both a widget and a panel on the same object, expect bad things to happen.
Currently it is a panel. It was a widget before for some reason so I changed it to see if it made a difference.
Also, not quite clear what you mean by culling in this case. Culling can be many things. Back face culling, occlusion culling, depth culling (more commonly known as a Z-test), etc.
That is the problem, I have no clue what it is. It just is the case that the widgets like Label, Progressbar and so on are not drawn in some cases.
On the image in the blue box there is a green progress bar and a text on the left "Happy:" which is not visible (no wireframe of the text mesh and so but active in the inspector). If I deactivate the prograss bar object (one of your controll prefabs) it gets visible.
Also the frames of two of the progress bars seems to be hidden by the "overlay" object.
What is drawn and what not is different by each start. Settings like depth, Z-value makes no difference at all.
Pretty important, this only occurs when I do gameobject.SetActive(true) of the selected parent object. When I activate it in the inspector during playmode by hand it does look fine.