When I place the grass tile over the ground tile, it doesn’t clip or blend properly—it just overlaps and looks like it’s floating.

I'm not sure what the issue is. It most likely is something about the grid; when I look at the files on my end, they overlap as they should. I've never had this issue come up before.
Some things that could be the issue:
- Sorting for isometric/2D is off
- Different import settings between the two sprites If PPU/pivot/mesh type differ
- Grid / cell size mismatch (the grid should be true isometric, not 1:2)