I don't think good washed sand should smell on its own. It's silica granules, right? But maybe there's also nothing in there to mask a strong smell.
So the ammonia is the smell, right? And that should evaporate if not held in or absorbed by the sand? What is it about sand that gets "wet" so easily, that absorbs moisture so easily?
What could you add to the sand to prevent odours? I did note that sand is best for a very dry environment.
Clean sand doesn't smell, but the poop dust in the sand rots and stinks when wet.
That's why, IMO, dry organic material is better than sand, with the carbon rich wood/straw/etc. neutralizing the nitrogen rich manure.