I my Chansey's Affection and Enjoyment at maximum, and have it's Fullness at max with it levels up, yet it has yet to evolve. Does anyone have any tips, ideas, or have an explanation to why it hasn't evolved yet?
Yes, it still evolves into Blissey when it levels up with a Friendship Value of 220 in Pokemon X & Y. Source
What your problem is is that Affection does not equal Friendship. You gain Friendship by walking around with the Pokemon in your party, giving it vitamins, leveling it up, massaging it in Cyllage City, using a Soothing Bag in Super Training, or using EV-Lowering berries on it. Source