Summary
On some computers, the latest feature update or cumulative update is not available via the Windows Update. When "Check for updates" button is clicked, Windows reports that "You're up to date", even though it is not true.
Body
On some computers, Windows 10 2004 (May 2020) feature update is not available via the Windows Update. When "Check for updates" button is clicked, Windows reports that "You're up to date", even though it is not true. The work around is to manually download and install latest updates.