In this guide ill explain how to get rid of the blue squares that can sometimes appear for mobs. To fix this problem go to navicat or whatever else you use and find creature_names find the mob you are having the problem with and side scroll till you see male_displayid female_displayid etc.. first check to make sure that id is right then go to male_displayid2 and female_displayid and make sure the 2 ones are set to 0 if there set to 1 make them 0 1 is what the blue square id is or any other id that isnt assigned to a display id will show as a blue square make sure the id that shows in male_displayid female_displayid is the display id you wanted and make sure its valid if its not youll have to change it one of my favorite ids is 15511 which is a silvermoon guard. That should fix your problem.
+Rep helpfull guides.