Problem with the Hub01 armor

Hello people.
I have found a problem with the Hub01 armor. Or I do not understand it correctly.
When I put on only the Hub01 modular defense system the protection values are calculated correctly.
But when I add the addons “ballistic mantle” and “prototype skirt”, the protection values of the things are not added.
At least that’s how it looks on the body status…

Does anyone have an explanation for me?

…Screenshots to look at…