I have the same issue on 6.7 U3.
I have a couple of machines which hasnt be upgraded in quite some time, upgrading these to 6.7 and later (version 14), it all works as expected, but if you upgrade to 6.7 Update 2 or later, it then shows unknown.
vCenter has been upgraded to U3 also as well as all ESX hosts.
VM's are still working but I do not like errors. You also error when you try and scan.
Any solution as I know theres no 'known' way to downgrade a VM?
Thanks in advance.