Thanks for the answer. The only breed on that list that should lay a blue or green egg is a Cream Legbar. That is not a Cream Legbar chick. I assume the egg was marked LO as they said they would mark each egg so you would know what breeds you had. That chick could be a Lavender Orpington, the color is what it should be. All chicks of other breeds listed should look different. But an LO should lay a brown egg, probably fairly light brown. I understand why you are confused.
I see two possibilities. They did not tell you the truth. The eggs are not from those breeds or they are not purebreeds. At least that egg.
The other possibility is that that chick did not hatch from that egg. A Cream Legbar hatched from that egg and that chick, probably a LO, hatched from a different egg. You are the one that hatched them, all I can do is throw that out for you to consider. I can't come up with anything else.