i think your PH needs to come up a bit, they like it best with a PH of about 7.2 to 7.8.
is your tank fully cycled??? the babies may even just be good hiders but i think the problem is the PH
i think most shrimp would love a PH above 7.0, they have an exoskeleton and a higher PH can only help them protect themselves.
is your filter covered to keep babies from getting sucked in? do you have some sort of calcium supply in the tank. mothers will throw their eggs away if conditions aren't to their likings. mine seem to do better with some calcium in their tank. they also seem to have a lot more babies if i give them a couple small smooshed pond snails a few times a week. my babies usually don't hide that well. they like eating algea off the glass.