Here is a clue.
The MS DOS Floppy disk that I have has the "fdisk" command.
I ran it, and it doesn't pick up any disks as below. (Below is MS DOS window in Amiga). THERE IS A 5.25" MS Dos Floppy in there or else it doesn't boot (so PC is fine)
So until that PC side see's the Hard Drive, I see no way the Amiga side could see it. (Even running PCdisk on Amiga side, would only pick up Drive available on PC Side).
"DJmount" as show above runs fine. (NO Error Messages, it enables bridgeboard to work perfectly. And doesn't see any Hard Disk, and that could be fine, just like no Controller Card/HDD)
I played around with the (Controller-HDD) ribbon cables since the picture showed one flipped around. Doesn't help.
I wonder if a Controller driver is needed for the HARD DRIVE to work with the Controller card.
** IDEA#1: I'm thinking is either Borrow a working Controller Card from the 286, maybe even the Hard drive, since that 286 has driver software **** IDEA#2 Reverse: Put AMIGA's Controller Card & Hard Drive into 286PC. Both with that Same 5.25" floppy and run "Fdisk" **