This happens in both survival and creative, happened to me, and my friend who both run the OSX version on our Macbooks

Whenever i try to expand a map (by putting paper around a map)

Produces the exact same size map (the smallest one there is)

Steps to Reproduce:
1. Start out by crafting or choosing a regular map.
2. Look at the map to have it reveal your location
3. Go to crafting table and put the used map in the middle, and paper surrounding it
4. Click finished product to get new map