Kind of ironic that I'm asking this after all support for the game has ended, but better late than never, I guess. I've completed many of the Gold-level mastery nameplates in MEAMP, but none of the individual challenges have been reset. This includes Map Mastery, Tech Mastery, and all the race Masteries. Is there a way to set these back to zero and redo them for more challenge points?
It would appear that masteries never reset. Here's a screenshot of the top-ranked players on PC, for challenge rating:
All the leaders have the same rating. If masteries could reset, you'd expect the leaders to be much more spread out (like for APEX rank). Instead, it looks like everyone listed here has maxed out all the fixed masteries and are now accumulating points solely from the daily challenges.