Golden gnome glitch

I have found all 54 gnomes when I go into the gnome catacombs or hall it says I am missing one going into all locations and checking multiple times by myself and with friends all 54 gnomes are accounted for and each is just an outline and won't let me pick it up. However by doing split screen with someone who hasn't obtained them I can press B and it will tell me for all 54 I've obtained them all. Keep in mind I've done this multiple times and don't understand why I'm not getting the achievement and why it's saying one thing in the gnome cata. And another at locations this is xbox one and deluxe edition preorder