BlockAll actually has nothing to do with the collision hull itself, it just says how to handle trace responses. Basically if a visibility trace response will return a hit or not in my case (click events are using visibility trace checks by default), or if an overlap might happen etc. The hull is always the same in all cases afaik.
If you want to remind yourself take a quick look here: https://docs.unrealengine.com/latest/INT/Engine/Physics/Collision/index.html
Well, whatever the reason for it is I’m aware of the solution now anyway so it’s all good! Thanks!