-When loading an existing Minecraft world with the new launcher, all achievements for that world are reset.

-I am using the same profile and Mojang account I have always used to play these worlds.

-I'm running Minecraft 1.11.2, and have done so prior to the new launcher.

-Only when I ran the new launcher did my achievements vanish for the selected world.

-I can load the world for a second time in the new launcher, and it remembers the achievements I have re-gotten since the first time loading with it.

Steps to Reproduce:
1. Load an existing Minecraft world with achievements gotten using the new launcher for the first time.
2. Opening the inventory earns you the previously-gotten "Taking Inventory" achievement.
3. Opening up the achievements menu confirms that all previously obtained achievements have been reset.