Did you use the search function to search for "Mastery" before posting? If you had, you'd have discovered a thousand other posts from people who can't get Mastery to work properly either. Best course of action is a simple, two step process: 1 - Disconnect the game from Dovetail Live. 2 - Forget that the sorry Mastery experiment ever existed.
The game updated today and lost all progress. Don't get me wrong game development is hard but having such bugs like this it's almost like Dovetail games does not patch the core mechanics of the game. This mastery progression system released last year expecting to work and still doesn't how is that even possible. You expect this to be patched in a few weeks not a whole year. Imagine playing a new call of duty and every time you logged in or updated the game all progression is lost it would get patched right away.