I know some loaches, like clown loaches bury themselves now and again, so it would be strange for them all to do it, then again they may be copying each other. Another thing with loaches is that if a tank is not properly cycled, they jump out, if there is no lid on your tank, i would check the area around the tank, the only other thing I can think of is like with your gouramis, they may be scared after the move, and if you have one of those hollow fake rocks or somewhere similar to hide, I bet that is where they are. This is the most likely solution.
