When I make a map, I must start at the smallest size. I make the map and explore it. When I get to the edge I get my crafting table and enlarge the map. The data that was on it gets erased and I have a blank map.

Example: I had a map that was 3/4 scale. I was outside of the area covered by the map and I enlarged it to 4/4 - the largest map size. The map I was left holding then showed no explored area (should have been the closest 1/4 to me, but it showed no explored area except for the fuzzy area close to the edge I was standing at. So I have to go explore the entire map again?

This is bad behavior. Pretend I just taped the other 3 unexplored sections to make the largest map - that is what I should have been left with, a large map with 1/4 explored.