Adding BitLocker Inventory Data
If there is no data in the device modal BitLocker status or the BitLocker Compliance page, you may need to enable the Bitlocker WMI hardware inventory class in either the default or custom client settings (preferable) that you have deployed to your workstation OS’s;
To enable inventory of BitLocker properties, go to the ConfigMgr Console > Administration > Client Settings…
Custom (or default) client settings > Hardware Inventory > Set Classes…
Search for “BitLocker”
You may need to also enable the TPM classes, so search for TPM and enable those too!
OK all of those changes. Your client systems will then return BitLocker state on their next hardware inventory cycle, so allow ~7 days before you have a complete picture.