Here, I think, is the problem: The Wiki recipe calls for adding the
P. candidum to the milk. Thus, it is contact with the
P. roqueforti when it is sprinkled on the draining curd. Not good.
Caldwell in Mastering Artisan Cheesemaking states on page 226 regarding a Cambozola recipe (Ann Hansen's Blue-Brie Cheese) that the blue can be hindered by the white when present in the milk. Hansen's recipe calls for
NO P. candidum in the milk. Rather it is sprayed on the cheese
AFTER the wheel has been pierced and the blue has had time to develop. This keeps the two molds separate, which is a good thing.