Your PCI account may have been configured with the option "Scan Dead Hosts". This is a subscription level setting that can only be enabled by an administrator. This setting affects the scan status for network scans that return no hosts alive.
By default, the scan status "No Host Alive" appears when no hosts were scanned because no hosts were "alive" at the time of the scan, meaning that they did not respond to probes sent by the PCI compliance service. A Scan Results Report is not available in this case because there is nothing to report.
If the "Scan Dead Hosts" option has been enabled for your subscription, then there is a slightly different behavior. The scan status returned when there are no hosts alive is "Finished". A Scan Results Report is available and includes the information gathered QID 45038 "Host Scan Time".