On a load all the yield icons are gone. They appear on tiles that:
Have borders expanded to.
Have been discovered for the first time by a unit (grey hex --> terrain).
Have their yields changed by a policy, improvement, or opportunity.
There might be other instances of it.
Have borders expanded to.
Have been discovered for the first time by a unit (grey hex --> terrain).
Have their yields changed by a policy, improvement, or opportunity.
There might be other instances of it.