Block not spawning in surface

Hello, and thank you in advance for any help!

I have created a block that is supposed to mix in with grass blocks, as a less common type of grass block. My main issue is that it wont spawn at all. I even tried raising the amount of groups per chunk just to see if I was unlucky, but I found nothing. I have it set to spawn in the surface and to replace grass, with the maximum generation height at maximum for different terrain heights. 

I am using 2023.1 for 1.18.2 if that at all matters.