OS updates
Could you please try this update (unzip and replace hostmon.exe module)
www.ks-soft.net/download/hm1256c.zip
Antivirus Status
Yes, that's correct behavior. Defender can be checked on Windows 7, 8.1, 10, Windows Server 2012 R2 and newer.
3rd party antivirus software can be checked on Windows 7, 8.1 or Windows 10.
Quote from the manual:
Check antivirus/antispyware status, uptodate state (Win 7-10)
This option tells HostMonitor to check built-in or 3rd party antivirus and antispyware software running on Windows 7, 8.1 or Windows 10 systems. Test will set Bad status when all antivirus products disabled or some software is out of date.
Check Defender: pending reboot/manual steps, critical failure
With this option enabled HostMonitor will check Defender running on Windows 8.1, Windows 10 or Windows Server systems (starting from Windows Server 2012 R2) and set Bad status when Defender requires reboot or some manual steps or critical failure detected.
Check Defender: alert if signatures age >= N days
With this option enabled HostMonitor will check Defender running on Windows 8.1, Windows 10 or Windows Server systems (starting from Windows Server 2012 R2) and set Bad status when Defender database is too old.
Regards
Alex