Prefab within prefab order issue (bug)

At the moment I'm forces to create a prefab in which I have x amount of another prefabs which need to be ordered in a specific order. However when there are already prefabs present, I have hard times to order them correctly. (UI elements)

First Gif is where I try to parent a prefab which seems not to want to parent as first child.
Second Gif is where I finally managed to parent it as first child, but when I exit the prefab workflow the order of prefabs is completely out of control.

Besides the UITab, all other prefabs were already present in the parent prefab. So I think when dragging the order ID's go totally messed up. When I exit the prefab workflow it even gets worse.

I can bugreport in the editor, but the project is pretty big which will take me some pretty long time to send in a small project where this issue appears. It's pretty hard to redo the issue so I recorded it.

Issue in: 2019.1.10f1