I noticed the same behavior a couple of times lately, not from Windows updates per se but from Microsoft Defender app. Tried to resume its virus definitions update manually to no avail, Defender just refused to update. At first I thought it was some nasty that slipped in which messed security settings or something like that. Strangely enough, on both occasions, it took a couple of restarts and files system checks to make updates work again. I also ran a thorough malware check with other av solutions that were smoothly.