I'm using the Dell Venue Tablet encrypted with DE 7.0 and managed by ePO 5.1
I haven't tried the on screen keyboard, but I can tell that when not forcing the keyboard to appear it is indeed not there. I haven't tried enforcing it so I can't tell if that options works.
Having said that, I'm using a new feature of DE 7.0 and that's TPM autoboot... Take a look at https://community.mcafee.com/docs/DOC-5520
It is SO MUCH better than on screen keyboard which even if would have come up is too small for tablet use.
The Dell Venue has TPM 2.0 so this feature allows to boot without pre-boot authentication prompt, and the drive encryption key is still protected by TPM. To complement that I'm using Reactive Boot so if someone tries to brute force or guess the Windows login and got it wrong for, say 3 times, the system restarts and then prompting for pre-boot password which will require a USB keyboard.
I don't have a Venue, but i've gone through similar pain with the Dell XPS12 and after about 4 months & MANY emails between myself, Dell Support & McAfee (and sending one of our XPS12's to McAfee engineering in UK); Dell have released firmware A04 which in combination of EEPC 7.0.3 addresses the issues between the 2 products.
I suggest contacting Dell Support & advised them to check that the required protocols are enabled in the Venue UEFI environment. If they are unable to help directly, perhaps suggest exchanging Dell & McAfee SR details and have them work together on resolving the issues.
Edit: I assume you are already running the latest public firmware on the Venue?
Thanks for the advice Everyone. Our Desktop Engineer is already working with Dell & Intel on the firmware side. We'll have to look into the TPM idea, but at least its an option maybe worth pursuing.
Good Luck... I'd be interested to hear how you go as I've got a team requesting these devices also. Apparently the XPS12 is too big & heavy (meanwhile its 1/3 of the size/weight of their previous Lenovo bricks).