I have an ASUS WS Z390 PRO (latest BIOS 0401) with a 970 EVO NVMe SSD and Windows 10 1809 (RS5), a TPM is also installed. I’m trying to use Bitlocker Encrypted Drive hardware encryption (aka E-drive, aka TCG Opal with IEEE1667). Windows is installed on the 970 EVO NVMe, so it is a boot drive. I have activated Encrypted Drive on the 970 EVO NVME using the option in the Samsung Magician software with a subsequent secure erase. Upon a fresh install of Windows 10, Samsung Magician reports Encrypted Drive as Activated, so it is enabled and ready to be utilized (but not yet encrypted). However, Bitlocker is refusing to use hardware encryption on this drive as long as it is a boot drive. As secondary drive everything works fine, so the procedure is sound. I already used the same procedure with a SATA boot drive, where it works as well.