Sophos sees an MBR on a GPT device

I've been coming across several systems that are using Sophos with Bitlocker where I cannot remove the client. When I try, I get an error that the MBR is encrypted and needs to be decrypted first. What's strange is that these are GPT systems (hence Bitlocker) so I have no idea what I need to decrypt. Even in the Sophos control panel if I choose the computer and go to the machine settings I have the option to back up the MBR. Anyone have any insight on this? This is Safeguard version 7.

Thanks!