Maps when upgraded in release 1.6.4 do not change their map scale

I thought that when I upgraded the map it would change scale

So I got 8 paper followed the recipe and it came out blank so I exited then re-entered the world and it wasnt blank but it had`nt changed scale

Steps to Reproduce:
1. Create a map with 8 paper and a compass
2. Upgrade the map with 8 paper
3. Exit the world then re-enter