Hi foxfish
Its strange to hear that your ones are always hiding, in my tanks I have a good platform for them to filter feed right in the filter flow, and they'll sit there for days, side by side, really not going anywhere else much at all. However its usually bamboo shrimp that do this more..
Its either that its strange that yours are hiding, or strange that mine are never hiding..
Either way, here are a pointers on feeding them:
If you do see them going along the floor using their fans to try and find food it means that they arent getting enough food by filter feeding - and this is bad because it can damage their fans to be going through substrate you see
So what usually works is, when feeding your fish thigs like pellets and flakes, if you crush some little bits up and place them in the filter flow then they get swept down into the shrimps fans and they then just eat that food.
Also, if your local fish shop has anything like 'liquifry' - basically a drop food that you add to the water to feed baby fish - then that is also easily taken by the shrimp