In a moment of “Well, I knew I was kinda right”, I should clarify the issue wound up being something fixed by Windows Update itself when I checked a few minutes ago (have been checking hourly), Security Intelligence Update for Microsoft Defender Antivirus - KB2267602 (Version 1.401.1026.0)
That’s all it took to fix my copy on my machine, YMMV, and sorry for cluttering the forum with my aggravated nonsense.