Thanks for flagging this. It's working as intended, but it isn't obvious. Bricks come from the EXP an action is worth, and leftovers carry over to your next action. A berry pick is a small action, so on your own kingdom's ground it takes about two or three picks to make one Brick: you'll see one on the 3rd pick, then the 5th, then the 8th, and so on. Chopping a tree is worth a lot more and gives Bricks every time. If you're harvesting on another kingdom's land, the Bricks go to their store, not your pack.