R320 BIOS 2.1.2 BitLocker Error

Its time to run updates again, but this time round we seem to be getting a persistant error when attempting to update the BIOS.

Our normal method is :

1. Suspend BitLocker
2. Apply updates that can affect TPM measurements (BIOS etc)
3. Restart
4. Enable BitLocker

But we get an error with the BIOS package even with BitLocker Suspended:

The update package cannot be run because the operating system is running Windows BitLocker Drive Encryption with TPM measurements. Please disable BitLocker and then run the update package.

Ideas? - Disable BitLocker means decryption, so that is NOT an option.