We have recently started ordering the Latitude 7480 Business laptops and seem to be having issues with Bitlocker passing the key to the TPM Chip.
We are building with Win 10 Enterprise image so BIOS is set to Legacy Boot rather than UEFI, but TPM is both ON and Enabled.
When we try and enable BitLocker it asks to restart the machine, on next boot in there is an error "BitLocker could not be enabled. The BitLocker encryption key cannot be obtained from the Trusted Platform Module (TPM). C:\ was not enrypted"
Doing some looking online seems there was a forum post on here just recently about the same issue and the issue was resolved by Dell releasing a new Firmware (V 1.3.3) for the devices which corrected the issue in TPM 1.2 - however these devices come with TPM 2.0, I have installed the latest firmware from their site (which is now V 1.4.6 which also includes a security patch for the Intel AMT system) but this still gives the same error.