Observer, auto farm pumpkin / watermelon

Hello! I noticed one bug related to the observer. The classic simple auto pumpkin / watermelon farm stopped working. In versions 1.14.0.0 and below, it worked fine.
The problem is that the observer does not notice a change in the block when the seedling bends / straightens.
I ask you to solve this problem, because there is no other way to make a car farm.