Stone instead of dirt

Hello everyone!

I am making a sculk cleanser. It's really basic for now, and it needs more work, but i have a basic skeleton on for now

i am, however having an issue where some blocks that should be turning into Grass turn into stone.

Here's a video of the issue. It's a minute long, but i wanted to show that this happens on a blank, newly created world

Cleanse Procedure and Right Click Procedure

can anyone help me with it? please and thank you