At this point, we've got several MS people running around in circles working on this. Since updates do not come under the purview of our usual contacts, they had to "reach out" to other people, who had to consult still others, with the result that we got
the post by "DK - MSFT," which was intended to settle the question but, since the profile was not authenticated, just muddied the waters. We've since gotten confirmation that DK is an official Microsoft employee, and I've marked her reply as the answer to
the original question of whether the popup was genuine, but we've resubmiitted queries about the other issues ("Why now?" and so on), and people are still looking into it.
We may never get resolution that satisfies the skeptics, but it seems that the update mechanism may (for whatever reason) have changed for this specific occasion (or perhaps as a policy for the future). Those who don't want dodgy-looking updates can turn
off the update option (as illustrated by ConfusedKate77) or continue to refuse them. Those who want to be patched up to date can accept the update at face value.
Thanks for the info.
Has it been confirmed to what version this update should be updating the software to?
Thanks