In the latest snapshots, when I place a map in an item frame, the map doesn't appear. It just looks like an empty item frame, only larger. This probably has to do with the fact that you can now rotate them 8 ways, although it happens even if it's not rotated.
Linked issues
duplicates
Comments
galaxy_2alex
Duplicate of MC-45764
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.