The problem is my additude.
I don't know why I'm so irritated by this but when I updated in Nov, Plesk overwrote my DNS default template and it caused me major headaches. Since then, I've been bitter about the software. I would switch to something else, but haven't had the time or motivation to migrate to another CP/Server yet. Basically, it appeared i was being forced to include a random NS instead of being allowed to use NS1, NS2.
The solution you provided did not exist when the problem first arose, so I overlooked the omitted dns record. That set me straight, and I see where my mistake was.
I suspect I could delete the ns record(s) at this point, and it would work fine, so thanks for setting me straight.