Recently I have been having some issues with villagers not panicking to zombies above Y:120, breaking some of my farms.  

Here is a video of the farm working below Y:120, as you can see the villagers are panicked when they are on the bottom bed: https://streamable.com/s7i88

Here is a video of the farm above Y:120, where the villager on the bottom bed does not panic: https://streamable.com/toh7u