Isn't this called the 'forest' bug. After selecting start locations the game is supposed to normalize the locations, so they are within a certain % of equal. The bug is in the order it normalizes. It adds forests before resources, so it fills up all the available tiles with forests, which then blocks it from adding any resources.
If i recall the 'full of resources' map script fixes this issue. The script itself is what is full of resources the maps it makes have the normal amount of resources. The script has most of the common map scripts modded to work with his fixes.