Thanks to a post by primortal in another tread, I went to the "learn more" link (located down the page from the "Check For Updates" dialog box); started the process. I ran into a "Something went wrong" error message, hit retry three times. 3rd time was the charm, and all went through; afterwards did another "check for updates"...and there was Firmware update 8/1, so I installed it too":^)
SP3 seems to be running great.... for the time being
Update: Here is primortal's post:
Nothing today via clicking Check for updates so a little below there was "Learn more" link which took me to Windows 10 update history page which provided a download to install the anniversary update.
The update went smoothly and after everything was completed, Windows Update had the 8/1 firmware update ready to install.