I bought a 4TB HDD to replace the original 2TB HDD. I cloned the old drive (a basic data partition) onto the new one, and Installed the new drive. I decided, since there are 3 drive bays, to leave the old drive in, but in a different bay (I’d already installed the new drive in its original bay). The system recognised both drives, so I decided to move the libraries to the old drive. All was well, until the system just stopped seeing the old drive. I checked connections etc (all OK), so I took the old drive out and put it in a caddy. No problems, and I reinstated the libraries. But, I’m puzzled as to why this would happen. Any ideas?