Probably the target host that you are scanning do not respond to icmp echo ping request. It may think that someone launch an attack against itself. So the host firewall on the target system may blocking what Nessus wants to do. So here are the steps you can do: Go to nessus > select the host and choose configure. Select the scan type as custom instead of port scan (common or all ports). Now go to host discovery and turn off the ping the remote host. Hopefully your scan should work now. Thanks Mahim Avi.
Kali linux mouse disappear issue fix 1. Shut down the VM. 2. Select Upgrade this virtual machine (right under Edit virtual machine settings) 3. Choose Next. 4. For Hardware Compatibility, choose Workstation 17.5 or later. 5. Choose Alter this virtual machine. 6. Choose Finish. 7. Power on the VM. Problem solved. Avi