anonymous user Thanks for posting in our Q&A.
To clarify this issue, please check if the device meets the system requirements in the following link:
https://learn.microsoft.com/en-us/windows/security/information-protection/bitlocker/bitlocker-overview#system-requirements
For EventID 851, this error may occur in that the device uses the legacy BIOS. We can read the following article to try to check the BIOS mode.
https://learn.microsoft.com/en-us/windows/security/information-protection/bitlocker/ts-bitlocker-intune-issues#issue-4
For Event ID 846, this error may occurs in windows10, version 1809 devices. Please check the device version, if the device is 1809 version, it is suggested to try to update.
https://learn.microsoft.com/en-us/windows/security/information-protection/bitlocker/ts-bitlocker-intune-issues#issue-7
Hope the above information will help.
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