When trying to design new Juggernaut, first time it works fine.
However, when you try to make a new design again second time some of his abilities get 'stuck' as not selectable or unelectable like this:

As you can see, his defensive trait is 'grayed out' and can't be unselected.
Reloading doesn't help but closing game and starting it up again fixes it ... until you try again to make 2 juggernaut designs in same game session.
Btw, I have run into similar bug in both FE and FE LH when trying to edit existing designs. Doesn't happen always.
Also, Juggernaut graphics seems somewhat corrupted when trying to design second time, doesn't show on first one I think.