When you have already a map with id 0 and create a new map, the map with id 0 stops updating. Reloading the world fixes this.
- If a map with id 0 exists already you can use
Otherwise create a new map by right clicking with an empty map
- Make sure the player marker moves when you move
- Create another map
- Look at the map with id 0 again and move around
→ It does not update anymore
The following is based on a decompiled version of Minecraft 1.10 using MCP 9.30.
The reason for this is that the method net.minecraft.item.ItemEmptyMap.onItemRightClick(ItemStack, World, EntityPlayer, EnumHand) currently creates server- and client-side a MapData object and stores it. This should not happen client-side because the client does not store the map id and uses therefor always 0. The problem is that if a map with the id 0 already existed, the net.minecraft.client.gui.MapItemRenderer registered it already, but because of the new map being generated with the id 0, the old map gets overridden. The MapItemRenderer refers however still to the old MapData which is not updated anymore (intended). The client should probably not create a MapData object in the first place.