Mine throw hidden traits just fine these days - in a rate that is a bit better than the percentage-wise chances, even - so I am not complaining about that.
My issue is genders, where my luck these days is so extremely bad that I've been on the edge of giving up all together. As in, completely. One evening when unboxing a kitten, I told a friend "If this one is the wrong gender too, I swear I send them all to menagerie!" - and what's worse, I actually meant it
(THAT one was then the right gender, and hence bought it's family and friends some time!)
However, I do not think this is a change in breeding behaviour, not in traits and not in genders - I just think Lady Luck (or whatever the "Force of Luck" is) enjoys playing games with us at times ;-)
-But yes, I understand your frustration - been there, am there, will be there again - it's the story of out lives as breeders of SL breedables ;-)