A deeper investigation suggested that the issue is probably with the combination of CentOS 7.4 and open-vm-tools-10.1.5 and not specifically with the Foglight as Foglight just displays what is collected via the API.
** CentOS 7.4 VM (open-vm-tools-10.1.5) **
PS C:\> $vmguest = get-vm FQDN | get-vmguest; foreach ($disk in $vmguest.Disks) { $disk | select Path }
Path
----
/
/boot
/var/log
/tmp
/var/tmp
But the same query returns accurate and desired results on CentOS 7.5 and open-vm-tools-10.1.10.
** CentOS 7.5 VM (open-vm-tools-10.1.10) **
PS C:\> $vmguest = get-vm FQDN | get-vmguest; foreach ($disk in $vmguest.Disks) { $disk | select Path }
Path
----
/
/var/log
/boot
