Yes, you have some threads discussing this same, or similar problem.
I had this same problem myself. In my case the USB connection was not stable, so I tried a different cable, but the same problem appeared.
I finally requested MNT if they could provide a replacement keyboard, since the change I had no problem at all.
Your cables seem fine, play with re-seating them to ensure proper connections.
Also ensure you’re running the latest keyboard firmware, as I understand latest versions were more tolerant to connection failures (although, I’m not 100% sure of this last statement :-D)