Need Help with Masteries (Possible Bug)

So I’ve decided to focus my first few games on the Delhi Sultanate and have been achieve the first mastery, which is to increase the yield of 6 berry bushes. This is accomplished by building a mill next to said bushes, however it does not seem to work, as I’ve yet to get the mastery. Do I have to win said game or do something else to get the mastery to register or is it just a bug.

I think you have to finish the game conventionally. I seem to recall exiting a game (I was losing badly) having completed a mastery and did not receive credit. AFAIK mastery credit occurs on the end-of-game score screen.

Just to double-check, are you sure the mill covered all 6 berry bushes? It has to have the little fencing around them.