How odd! The first level of mastery requires 8 servings so you should've moved into level 2 by now.
This doesn't seem to be a widespread issue as my Fruit Trail Mix counted normally. I served all 37 which left the mastery bar about 1/4 of the way on level 3, as expected.
I'd suggest watching the bar and if the problem persists, open a Support Ticket with the team.