Sand actually can grow grass (and clover), although it does present some challenges.

Here, what looks like what's happening is called "sprout and pout." I'm not sure of your locale, but this is characteristic of both warm season and cool season grasses.

What happens is the plant extends a leaf or three post-sprout, but then spends more of its energy working on the root systems than anything else. This makes sense--without roots, lush leaves can't be maintained. Without many leaves, the root systems do just fine.

Pouting lasts until the root systems are a little more developed. Right now, for northern lawns, pouting is standard--they simply don't grow much in summer. The clover will come out of pout phase much faster, the grass probably not until September.

For now, keep it watered appropriately and skip feeding until temperatures drop for fall (for northern lawns, southern ones differ).