I suspect the problem lay in the, unknown to me, process by which the drive, when the tray is closed, detects a disc This worked for CDs, blank or burnt; and worked for blank DVDs, but didn't work for ANY written DVDs, whether commercial ones or my DVDs.
The verify process doesn't open and close the tray.
The fact that the written & verified DVD was perfectly readable on my laptop suggests the verify process was OK. And having used Nero for many years I've never had an occasion when the verify process finished OK but the resultant disc was not OK.
Happily running Windows 10 Pro on both desktop and laptop
We have more and more laws, and less and less enforcement