Farmers in 1.14.4 cannot craft Bread. My initial suspicion was jammed up inventories but further testing led me to revise my report. I am confident this one is accurate now.

To test I created 4 identical farms - 9x9 farmland with water in the center with 4 composters on the 4 corners of the water source. In two farms I planted wheat and in the other farms planted all other crops. There is a wall between the farms to keep the wheat only on the left side of my image. I then created an overflow area on both sides with extra beds so the baby villagers would run down - essentially creating an infinite breeding situation. On the non-wheat side the farmers will feed those villager as well when it's "bell time." As you can see from the image no breeding took place on the side with the wheat. The other side spawned 162 villagers over about 14 hours (it says 178 but I have 8 farmers on both sides).. Examination of the NBT data initially led me to believe the wheat farmers' inventories were filled up so they could not craft bread - similar to an issue I posted about 5-6 years ago. This time they are not attempting to craft bread. Thus, no breeding. The danger here is when farmers get access to seeds it becomes the default crop - thus leading to a village unable to breed at all.

Not only is having seeds by default a bad idea but I really think farmers should stop harvesting wheat. It has been nothing but problems since the 1.8 snapshot. You can easily solve this problem by preventing them from harvesting wheat. I also believe given enough time they would also jam up on beetroot since it gives beets and seeds. Since seeds are not food any seeds have the potential of filling up all 8 inventory slots.