Hello,
"And it seems that there have been no new patches or releases in the last 90 days."
Sure there have been patches in that time - last ESXi patch was released 36 days ago:
There are numerous different reasons why this won't/can't update - start by checking the date of the one in use, if it is old then get a current one, if it remains using an old one when you are manually applying a current downloaded then it isn't updating. Some common causes here:
If you have internet access from the vCenter then try updating from the vCenter in the HTML5 Client if 6.7 U1 or Health alert in the later 6.5 versions *IIRC*, if it is not pulling the current one and you have proxy configured then you may need to ACL more than just the myvmware login address, if you don't allow *.vmware.com then check that these are accessible:
depot.vmware.com
my.vmware.com
vcsa.vmware.com
download2.vmware.com
If 6.7 U1 and vCenter is internet-connected and the above is not working after sorting any proxy issues try changing the defaultmetadataurl:
Bob