I have mealwood planted in farm tiles, and when my food supply is overflowing storage I disable harvesting on them until food supplies drop, and then enable it again. Just recently with the test branch this seems to no longer work, and they are still harvesting the plants when harvesting is disabled.
Edit: I continued playing the same save, set all the plants priority down to 1 and they finally stopped harvesting. Later, switching priority back to 6 did not trigger them to start harvesting again immediately, but after leaving it for a couple days they did begin harvesting the disabled plants.
Steps to Reproduce
Plant mealwood in farm tile Allow it to grow for a harvest cycle or two Disable Harvesting Watch as dupes still harvest
This issue has not been confirmed by a developer yet.