windowscentral[.]com/microsoft/windows-10/microsoft-admits-that-windows-10-is-wrongly-telling-users-theyre-out-of-support-heres-the-fix
Microsoft says it will be fixed in time for this month's updates, and this article also has a link to an .msi file that allegedly fixes things. I tried the .msi file in a VM with I'll say dubious results. I found that Windows Update was headlined with a banner saying support had ended, there was no Check For Updates button, but there was a Retry button, with text saying that an update couldn't proceed because of other updates currently running. I clicked Retry, and after seemingly searching for updates with none found, the Retry button turned into a Check Updates button. I then installed the .msi file, and nothing changed. Maybe the update that didn't work, that had to be *retried*, was the same fix delivered online? At any rate there was no clue whether the extended updates [ESU] were enabled or not. If you want to check for yourself, type slmgr.vbs /dlv at the Command Prompt running as admin. [or a Terminal tab] & press Enter.