Bone meal doesn't work on certain patches of grass blocks

I was trying to find the flower gradient in a flower forest biome by bone mealing all the grass blocks so there is a flower everywhere but one spot doesn't grow any grass or flowers, but the bone meal still gets consumed.

Video: https://www.youtube.com/watch?v=mmT8vEQuGgQ

World Download: https://drive.google.com/file/d/1YkoyQO6cExMJBS7D34z5Yg440VGV3OLa/view (huge)