One of the Stone Resources can’t be reached cause, i think, a smaller one is in the path, my Miners always try to go for the big one and end up standing around wondering how to get there until i tell them to mine the small one it’s still there so i try to farm it away and see if hey can reach it then just wanted to tell you 
Thank you Raistorm 
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In this case I assign the little stone for mining first in the automatic menu and the big one later.