Shield changes position when holding a map in the right hand

When you are holding a shield in the off-hand and take a map in the right hand, the shield for some reason changes its position for a bit.

To reproduce:

1. Get a shield and a filled map.
2. Put the shield in the off-hand and hold the filled map in  the right hand.

Observed:

For some reason, the shield goes to the right for a bit every time the player hold the map, and also gets a little smaller; however, it gets back to normal when the player holds anything else.

Expected:

The shield remains in the same position when you hold a filled map.

Notes: This does not happen when the map is in the off-hand and the shield on the right hand.