^{Update by Mega_Spud:}
Summary:
Newly created maps are blank when opened, but will update and show the player position icon when held in the off-hand. Moving the filled map back into the main-hand will stop new progress updating again.

Treasure maps are also affected; the player position icon does not update correctly, meaning the player cannot use the map in their main-hand to find treasure.

Steps to Reproduce:

1. Start the game in 1.5.0.10 Beta
2. Create a new world (Seed picker "Village Island" seed:  -1060246543)
3. Obtain and open a locator map
4. Locate a shipwreck with a treasure map (Above seed /tp 24 ~ 56)
5. Obtain and open the treasure map
6. Now move either of those maps to your off-hand

Observed Results:
The map will not work as expected when in the main hand (hotbar slot). The player locator icon does not move for treasure maps.

Expected Results:
The map should work and update correctly in either hand.

Screenshots/Videos attached: Yes

Notes:

Original Description:

Hey i found a bug