Winnie

I have this issue as well, and it does the same with the woodland mansion / water monument maps. Happens in every world I have tried, and a friend has the same issue as well. It's very frustrating. 

I created a new map as well, and it does the same - broken treasure map. normal maps work fine though! I am still not sure about woodland / ocean monument maps (it says in the issue it does, but that was a autocorrect error)

edit: woodland maps seems to work fine! (done in a creative world)