Ever since the last update, my dark plate armor has looked like white leather armor, and the wings and tail from the tails mod will not appear. Is this something that happened on server's end, or is it a wide spread issue for everyone using the mod pack?
Are you using the MYM launcher? If you are, the built in HUD "disables" the models for the tails mod. Not sure about the leather dark plate maybe the MYM HUD doesn't like the texture?
