Maps that are placed in item frames and are the map containing the location where the item frame is located in the world sometimes lose integrity after leaving the area.

I have map rooms in my world. The center map is my home base, and then I radiate out from there, mapping as I go.

Usually, but not always, when I return after an excursion, the level one map containing my home base no longer shows my home base. It only shows the green marker for position.

If I remove the map from the item frame and replace it, integrity is still messed up, although it sometimes shows part of the map.

If I log out of the game and go back in, integrity returns. So, it seems to be a visual effect only. I'll try to add a picture the next time it happens.

NOTE: I tried to search for other bugs of this nature, but couldn't find any reported.