Hi
It looks like the AI assigns European units to the least producing tile.
See save game file (attached).
Look at the English tobe Colony at 33, 85 (I play Dutch - so use --debug MENUS)
At the next turn AI will assign one colonist to produce ore on the grain resource (34,86) and one unit producing grain at boreal forest (33, 83).
I think the bug is caused by a wrongly sorted workplan in ColonyPlan.java.
A patch is attached as well.
I have played a couple of games with the patch applied and it works ok for me. I have not noted any side-effects with the patch applied.
I am at master 75e1cf3.
/////Björne
And the save game
fixed via github pull request. testing looks good.