When you're holding a map in your off-hand or if you have something else in your off-hand while holding a map in your main-hand, the map will not update until it is switched to another hand.

What I expected to happen was...:
The map would update as I would placing blocks with my main hand

What actually happened was...:
The map wouldn't update, and I would have to refresh it every one in a while by double pressing F to switch it into my main-hand then back to my off-hand

Steps to Reproduce:
1. Get a map
2. Hold map in your main-hand
3. Press F (or place the map in the off-hand slot in your inventory)
4. Place/brake blocks and the map will not update until moving it into another slot or by pressing F