Placing grass on chiselled dirt blocks

[Jyanin]

I think the reason was something to do with messing of the textures between chiselled blocks.

Search found it:

Sq and bevel chiseled blocks

it would be nice to be able to lay grass on beveled and sq chiseled blocks. also to be able to bevel and sq chisele resource blocks like fossles and copper.

Inside that thread, a proper answer:

Release 182 - Report issues here

We just don’t support square/bevel chiselled grass, and adding it would be a (I cannot understate this) a HuGE amount of work (grass relies on texture blending for the look, and supporting texture blends on square/bevel chiselled shapes would literally be months of mind-numbing work)