No, of course not.
The problem is that all of the things "in" the GUI element think they should be 0... which is why the preferred size is calculating z at 0. So it's all flattened and the collision picking stuff can't figure out what you've clicked on.
Forcing the preferred size of the outer element to something is only hiding the problem. The issue is that your elements themselves are all flat for some reason. Some kind of non-standard configuration of them or something because normally things like QuadBackgroundComponent, etc. all default to have some z size.