Configure the Custom WMI using below data.
Refer link how to configure:
https://www.sapphireims.com/help/Custom_Inventory.htm
Use the below WMI details
ClassName: Win32_EncryptableVolume
Namespace : Root\CIMV2\Security\MicrosoftVolumeEncryption
AttributeName: ProtectionStatus,DriveLetter
If we configure following will the configure Screen will be shown
Post the custom inventory collection the data will be shown in the CustomWMI page like below.
Reference Link: