Minecraft treasure maps simply do not work. I can never go to the NW end, the maps don't fill out, and it always gets the area wrong (ex: it'll say I'm in water when I'm evidently on land). I also collected about 7 treasure maps from vastly different regions, yet they all showed the same incomplete map, with my person in the exact same spot. To recreate this, I really only have to pick up a treasure map for it to create this glitch. It does this with ocean monument and woodland maps as well. 

thank you for your time!