Quest "Bronze Mine buffs" - Use 2xFish Platters on 2x Copper mines.
THANKS GOD I only 2 Spooky Bronze Mines and 2 endless Copper Mines, I can still build regular copper mines for the buff.
But if you have all your copper mine slots filled with "premium buildings" then puff goes the magic smoke from your building to progress trought quest.
GG as fish platter buff for quest works only on regular coper mines
Now gimme a candy j/k
BB should by now figured, that some people wouldn't have regular mine spots free left.