I have filled it with 2 new 8TB drives (HDD) and 2 new 1TB drives (SSD).
The is that the 4-Bay SATA cards seems to have stopped responding.
All four drives worked and mounted just fine.
However, now all four drives can no longer be found in Open Media Vault. (see below)
The drives no not show up in the terminal either [lsblk]. (see below)
You may contact cs@argon40.com you provide the information (issue, name, shipping details) and request for a replacement board.
But I would suggest that you make sure that the physical connection of the HDDs and SATA board is fine and the HDDs are securely screwed at the back plate. Then try to remount your drives.
I have the same exact issue with my 2 ssd’s. It goes “missing” after about a day. After I reboot, they reappear. I’ve reseated the pi and boards and its level. But same issue here. Did you fix it?