They sound scared of humans for whatever prior reason which sadly happens to a lot of fish. They may do better in a tank not being transparent for a while. This way they can't see you...at least its worth a try. You can cover the sides with something black.
A few years back I bought a group of clown loaches. The moment I opened the door they swam into hiding, very violently at doing so..Discus tanks are mostly bare, so the fish can't hide increasing the stress. It took me years of patience and the fish did overcome the fear of me, or any human. I was very gentle at water changes and there were times when I crawled into the room so I don't spook them...That was roughly over 5 years ago..Little by little they started trusting me, stopped hiding when I am in and in fact now they are in a puppy stage where they bunch at my hands for food.
They are now living in a black round pond and this has helped them tremendously to come out of their shells additionally...So it depends on the fish but I am finding out that fish kept in non-glass tanks are more outgoing and confident of their surroundings.
As for discuss...I've read this happens a lot. You need to try to reduce stress to a minimum, banging doors, lights being turned on and off without schedule, etc..They can damage themselves otherwise.