You need to post some photos of the console and computer, as it is very difficult to interpret a description of the issues.
In particular :-
50 ribbons connections at console, computer, and within the computer.
Within the console frame, under the faders (fader bus card).
Under the console - with interest in the 20 way S16E cable.
Are you using a computer bypass unit (1RU, located in computer rack).
I suspect something is not plugged in correctly.
Anthony.