If you have a map created on the Overworld, and take it to the Nether, and back to the Overworld, it will appear as the map looked before you entered the Nether. Relogging solves the problem.
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Duplicate of MC-46345 - If you have not, please use the search function in the future, to see if your bug has already been submitted. If you could not find the original report, please comment with the keywords you searched for.