So I've been playing on my survival save for quite a while now,and I realised that some crops that I placed underground do not grow at all,and that the crops that didn't grow were all diagonally next to each other. They all extend from the water source to the end and I couldn't find any pattern of the ungrown crops.
Steps to reproduce:
1. Create a 9x9 field of farmland
2. Put water in the center
3. Wait for the crops to grow
I tried this above ground on another creative world and this did not occur