Receiving invalid data via WMI - powershell

Question

I've had a script running for the better half of a year now that checks for disk space, should it be low it sends out an email been working just fine.
Today I received an alert saying that that Disk space was at 0gb.. I logged into the server and had about 30gbs available.
Part of code that checks the space.
[decimal]$thresholdspace = 5
$tableFragment= Get-WMIObject -ComputerName $computer Win32_LogicalDisk `
| select __SERVER, DriveType, VolumeName, Name, #{n='Size (Gb)' ;e={"{0:n2}" -f ($_.size/1gb)}},#{n='FreeSpace (Gb)';e={"{0:n2}" -f ($_.freespace/1gb)}}, #{n='PercentFree';e={"{0:n2}" -f ($_.freespace/$_.size*100)}} `
| Where-Object {$_.DriveType -eq 3 -and [decimal]$_.PercentFree -lt [decimal]$thresholdspace}
So I opened up an ISE session and did the following.
$computer = 'Server_01'
Get-WMIObject -ComputerName $computer Win32_LogicalDisk | select __SERVER, DriveType, VolumeName, Name,FreeSpace
and it responded with:
__SERVER : Server_01
DriveType : 2
VolumeName :
Name : A:
FreeSpace :
__SERVER : Server_01
DriveType : 3
VolumeName :
Name : C:
FreeSpace : 31372767232
__SERVER : Server_01
DriveType : 5
VolumeName :
Name : E:
FreeSpace :
So I then ran the part of my code that is getting space and it returned with the following:
__SERVER : Server_01
DriveType : 3
VolumeName :
Name : C:
Size (Gb) : 0.00
FreeSpace (Gb) : 0.00
PercentFree :
So I ran the simple WMI query and it responded with no data..
__SERVER : Server_01
DriveType : 2
VolumeName :
Name : A:
FreeSpace :
__SERVER : Server_01
DriveType : 3
VolumeName :
Name : C:
FreeSpace :
__SERVER : Server_01
DriveType : 5
VolumeName :
Name : E:
FreeSpace :
Any idea as to why I'm getting invalid or what appears to be incomplete data? I've never seen anything like this, and have not ran into this issue at all before. Nothing has changed on either server it is running from.