Comment 1 for bug 1813626

I see the same problem, see https://ubuntuforums.org/showthread.php?t=2411319&page=2&p=13834468#post13834468

apt-cache policy update-manager
update-manager:
  Installed: 1:16.04.15
  Candidate: 1:16.04.15
  Version table:
 *** 1:16.04.15 500
        500 http://us.archive.ubuntu.com/ubuntu xenial-updates/main amd64 Packages
        500 http://us.archive.ubuntu.com/ubuntu xenial-updates/main i386 Packages
        100 /var/lib/dpkg/status
     1:16.04.12 500
        500 http://us.archive.ubuntu.com/ubuntu xenial-security/main amd64 Packages
        500 http://us.archive.ubuntu.com/ubuntu xenial-security/main i386 Packages
     1:16.04.3 500
        500 http://us.archive.ubuntu.com/ubuntu xenial/main amd64 Packages
        500 http://us.archive.ubuntu.com/ubuntu xenial/main i386 Packages