What I expected:
Villagers to farm like normal.
What happened:
Villagers stopped farming and instead just got locked into staring at cocoa beans.

Steps to reproduce:
Unconfirmed if this has to be an existing village, but it is the easiest way:
Find a village.
Replace the bordering Oak Logs from one or more of the preexisting farms with Jungle Wood.
Plant Cocoa Beans on side of Jungle Wood.
Brown-coated Villagers will eventually, when they cross paths with the matured beans, with a matured farmland (Wheat/Potatoes/etc) will stop at the beans and simply stare at it, but not farm anything. After staring, they refuse to move until the Cocoa Beans are removed.