Solved
Mastery... No idea what this is....
Is mastery unavailable in a profile as soon as you leveled one/some/Most/all plants? Got some maxed out but never saw a Button for mastery.
Plants without Mastery: Mints, Power-Lily, Gold Bloom, Tile Turnip, Intensive Carrot, Perfume-shroom, Gold Leaf, Thyme Warp, Imitator (plant copy has the same mastery as the original), Marigold.
FAQ Mastery: https://www.reddit.com/r/PlantsVSZombies/comments/9zbe7n/mastery_explained/
