Windows: Windows 10 Enterprise BitLocker keeps asking for recovery key on reboot

After further investigation I have discovered the following:

Running tpm.msc I see the TPM status is: The TPM is ready for use, but with reduced functionality.

Checked boot type. It is set to Legacy not UEFI

Next steps:

Decrypt bitlocker

Convert disk to GPT

Enable UEFI

Enable BitLocker.

By M. Ketley