@GM46 - take a look at the following related thread :
I would recommend removing all of the SATA drives and then (using a single hard drive) test each SATA connector individually. In my case, only one of the SATA connectors was problematic (likely power related).
Also - note that the Argon support team is currently out on holiday, returning to the office on 20 February.
I will try your suggestion. What I did try is connecting the whole SATA board to a Linux Mint computer and also one running Twister OS using the USB3 jumper removed and keeping the power on the EON so that the drives had power, still the same issue. But as you said I will try each connector individually.
I want to ask if there is any Diagnostic app that runs in Bullseye or Linux that can stress test the connector using a GUI or in the Terminal.
A Linux distribution agnostic method to stress test the SATA board would be to connect two individual hard drives, ensure that Smartmontools monitoring has been enabled, and then perform an rsync job (between the two drives) for a number of hours.
Also note that your Seagate 2.5 inch hard drive (and possibly your Seagte 3.5 inch drives) will likely need USB quirks applied (to disable UAS) : SAT-with-UAS-Linux – smartmontools