I copy a Post from Barog90 here wich sums up the only bug known so far in this game.
(And a solution from him too?!)

Barog90 Vor 3 Stunden
Hmm, unsure if this said anywhere in here massive amount of comments. But might have some sort "fix" for that additional factories focus ( can't remember name...) been playing other mods and realised something. Every focus that add factories ALSO adds building slots. Think this is problem. Focus adds factories right, but as there is no "room" for them in the province. Well think you get what I mean. Perhaps spread them, or make less factories at starting? Think there was quite much buildings at Warrington. was around 38/18 or something. Sorry for stupidness, but writing this at half sleep, thus bounding making mistakes.

I have noticed this too, even after getting all the NFs that give you factories in lancashire you dont actually get all of them - the province seems to fill up and not allow anymore structures (civ facs military facs and dockyards too)