I tried enacting the colonial hub decision and it didn't give me a core in the province. I don't know if it's related to the fact that I hadn't enough money at that time (I was only testing to see what it did).
Also, is there some kind of block against gaining cores on unlawful imperial provinces? I've conquered Masha (as Firenze) around the beginning, 1360 or so, and two hundred years later, it's still not a core.





















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I used this in VIM to clear it out:

























