Moving my iTunes data
I have three separate music collections and I would like to make them one. One was on my iMac. To add the other two, I had to put my music on a portable hard drive 12 TB. I followed the Apple help instructions for moving my existing library to the portable hard drive, and that worked. When I imported a second collection of music, it worked fine, but a couple of days later, the new import was gone and I only see the original library. Does this indicate I did something wrong? The portable hard drive is connected directly to my iMac, and both is always powered up, although I reboot the iMac from time to time. When I did so, my latest import was gone and I was back to my original library/collection.
iMac 27″, macOS 10.15