Farming mechanics have changed in that it is much rarer for a potato farmer to give away his harvest. A carrot farmer will just continue planting, harvesting and sharing with a villager but a potato farmer shares very little for the first couple of harvests and then stops. This is a change in the last release because both worked perfectly before. Now if you present a farmer with a mixed crop everything gets harvested, the carrots are given away, potatoes are planted and at a certain point (I expect when the farmer's stacks get full of potatoes) the farmer just stops. I appreciate that before a farmer may swap to either only all carrots or potatoes but it never stopped them farming - now it does.

I am surprised that many more people have not reported this ( and I did search!) so perhpas it is an iOS 10 problem only.