In vmware.log on the Nutanix Controller VM (CVM), you see something similar to the following:
2019-12-15T15:20:36.683Z| vmx| I125: FileIOErrno2Result: Unexpected errno=5, Input/output error
2019-12-15T15:20:36.683Z| vmx| I125: ToolsISO: open of /usr/lib/vmware/isoimages/isoimages_manifest.txt.sig failed: Error
2019-12-15T15:20:36.683Z| vmx| I125: ToolsISO: Unable to read signature file '/usr/lib/vmware/isoimages/isoimages_manifest.txt.sig'.
2019-12-15T15:20:36.683Z| vmx| I125: GuestOS: GuestOS_GetToolsImageName: Failed to get Tools ISO image path.
2019-12-15T15:20:36.683Z| vmx| I125: TOOLS updated cached value for isoImageExists to 0.
2019-12-15T15:20:36.683Z| vmx| I125: VMXVmdb_SetToolsVersionStatus: status value set to 'unmanaged', 'unmanaged', install impossible
2019-12-15T15:20:36.709Z| vmx| I125: Guest: *** WARNING: GuestInfo collection interval longer than expected; actual=60 sec, expected=30 sec. ***
The ESXi hosts have the 'ProductLockerLocation' Advanced setting configured, and it may be pointing to the Nutanix datastore. As per Nutanix Support, this is unsupported. A local datastore is supported. It is not clear whether Nutanix supports any remote ProductLocker location.
Nutanix recommends changing ProductLocker back to the default, followed by a host reboot.
esxcli system settings advanced set -d -o /UserVars/ProductLockerLocation