They are trying to train you to continue feeding BS. Simply stop. Feed a small amount of flakes. If they dont eat, do not feed them BS again. They will eat the other food when they get hungry enough.
I agree...they are training you to feed them the brine shrimp!! LOL My discus did this as well. You have to just stop feeding the brine shrimp. Offer flake in 24 hours. It may take several days...but eventually they will eat it.
I can only comment on freshwater...don't know how sensitive salts are...but I would sometimes have to go several days with my discus when intoducing a new food. They need to get real hungry...one day isn't enough.