Dell E7250/E7450 - McAfee Endpoint Encryption, No boot disk

Hi,

Hopefully someone can help with the problem we have.  We have purchased several E7250 and E7450 laptops, which we've managed to configure with our corporate image but, when applying McAfee Endpoint Encryption v5.2.12, the following reboot reports an error at startup

"Error: 0xe002001b

No Boot disk was found"

We've applied this version of EEPC to all our previous Latitude models without issue, it's just this new model range. 

We've tried imaging using AHCI and RAID, other don't change the outcome.

If anyone has an answer to this, we'd be most grateful.

TIA

Darren