Hello,

in _vmware_vim_base.py you will find a possible explanation

def check_os_name(os_full_name):
# detect VMs which have 'or later' or 'other' in the GuestOS description
# This means that we have a new OS version running on an old VMware version which is not aware of the newer OS version
# trying to detect values like: 'Microsoft Windows Server 2016 or later (64-bit)' or 'Linux Other'

   exact_os_detected = True
   key_words = ['or later', 'other']
   ambiguous_o_smatcher = [word for word in key_words if word in os_full_name.lower()]
   if ambiguous_o_smatcher:
       exact_os_detected = False
   return exact_os_detected

If you check in vCenter WebUI you will see that the VMs reported without OS description actually have 'or later' or 'other' in their description.

The 'or later' happens usually when the actual OS version is not supported by that particular vCenter version. For example you can install a Windows 2022 server on a vCenter 6.7 but in the OS version drop down menu you will have only Windows 2016 as the last version and Windows 2016 or later which will be used most of the time for a Windows 2022 VM. When we query that information we consider it irrelevant so we avoid modeling as it will just cause data flipping with other jobs like HostConnection by Shell.

 If you do want always report the inexact value then change in the above script the last line from 

return exact_os_detected

to

return True

This means that no matter the OS description value (it contains or not or later' or 'other' ) it will always model that value.

\Bogdan