Each breeding's chances of making hidden + hidden is COMPLETELY un-related to what the cats earlier made. So, each breeding has a 25% chance, and it doesn't matter if they ever did it before or not.
I've also had cats that lived a full life and never threw hidden + hidden. I had no less than TWO pairs both hiding porcelain and they never threw it. Ever! -But now my NEW porcelain-makers just had their first kitten, and tadaaa! -PORCELAIN!
Random is random - but yes, I do feel your frustration! I think we all had experiences like that and some point with our kitties
Saga