While playing the newest snapshot, I made a wall of maps. While enlarging an existing map I realized that map #0 became odd looking-with nothing other than small strips of terrain near the top center of the map. I reloaded the save, which fixed the issue, however whenever enlarging another already-existent map, the same issue occurred. I reloaded and repeated process with multiple different maps, and the same issue occurred each time. In further testing, it did the same on other saves.

To recreate:

1. Have a variety of maps from different locations
2. Enlarge one of the created maps in a cartographer's table