I used paper to change the scale of a map. It worked fine for the first time but the second time the map was just a blank canvas and only a few blue pixels of water could be seen in a corner. I used a itemframe to display this broken map and it just showed a green arrow on a blank canvas (with the few blue pixels). Then I logged out and reloaded the game and the map had the previous scale level and was viewable again but it had a permanent green marker when I was holding it in my hands - and the paper to change the scale earlier was lost.