Systems Deployment

Hi all -- just beginning to explore the possibilities of UEFI deployments.  For now, deploying via UEFI USB drive, until my university network people can make the proper DHCP scope changes to allow for PXE UEFI booting.

I have successfully performed a few UEFI boots, using task suggestions I found here on ITNinja.  I have a pre-installation DISKPART script, and a mid-level bcdboot task that I'll paste below.  This deployment (using an existing .WIM Windows 10 image) has worked perfectly on a few new Latitude 7480s as well as a Latitude 7280.  But on a Latitude 5289 (Dell's new convertible 2-in-1) I get a "no boot device" found error after deployment.

I have the 5289 in my Driver Feed, and rebuilt the KBE with those drivers included (as well as the 7280 and 7480 drivers).  I can see the proper drivers pulled over during the deployment sequence.  The Windows files are there -- if I open a command prompt, I can browse C: all day long -- so I don't think it's a storage driver issue.  I think it's something with my DISKPART or bcdboot tasks, but I can't figure out what, and I can't figure out why the 5289 behaves different from other hardware.  (This is the only 5289 I have right now, so it's a population of 1 for testing.)

Here are my scripts.  Would appreciate any suggestions!