Now I know that I'm going to return this set, because it seems to have some kind of unique copy protection. Each drive that I encoded a disc from only worked for that one disc, and afterward it can't see any disc from the set. This happened on 3 out of 3 of my drives. At first, I thought that it must have been a problem with my encoder, but the problem remained, even after I reinstalled it. I put some other DVD not of this set, into any of my drives, and the encoder and DM sees them as usual.
I then went to Disk Management, and noticed that when I place a DVD from the set into a drive, the drive letter disappears for that drive, and DM doesn't display any data about the drive content as it usually does. Remove the DVD, and the drive letter immediately reappears in DM. It seems that they have all bases covered to insure that no one can enjoy these DVDs. The file manager doesn't even see the DVDs either.