Cannot enable credential guard on Latitude E5470

Hi,

I'm trying to enable credential guard on my e5470, without success.
Device Guard and Credential Guard hardware readiness tool says:
"Machine is not Device Guard / Credential Guard compatible because of the following:
HSTI validation failed"
Another issue is when Hyper-v Hypervisor feature is enabled, I can't shut down the notebook. When I click on shut down, the machine puts itself into airplane mode, and goes to sleep instead.
All drivers and bios are up-to-date, the OS also.
Do you guys have any idea what could be a solution?

Thanks