I use a mod that has a Size trait affect The Strength roll. It needs to use Traits to work. And I think the reason that the skills get screwed up is because their maximum increases beyond d12; it is a function of the skill being raised on an advance and not because of Professional or Expert (which are obsolete in my rules). The professional edges like Ace and Thief only work with my mods at Traits. When I thought it was an error is that I forgot that my house rule would affect it.