Xenial CloudImage wont boot on newer Vmware ESXi hardware version 11

I'm ruing ESXi 6 under vSphere 6 Enterprise Plus utilising most of the ENTPLUS Features.

I have taken the latest Xenial cloud image from:
https://cloud-images.ubuntu.com/xenial/current/

Converted the VMDK to ESXi format with vmkfstools, set PW on ubuntu user, removed cloud-init and generally just got everything working exactly as i want it (done apt-get update) This all runs fine with the VM configured with vm hardware version 10 and below. (ESXi 5.5 compatible)

If i upgrade the VM Hardware to v11 the machine will no longer boot (see attached screenshot)

I have successfully installed ubuntu 16.04 from the ISO onto a v11 VM without issue and also Ubuntu 16.04 is on the vmware guest OS support matrix as fully supported.

presumably there's *something* inside this cloud image that doesnt understand the vm hardware version, but does anyone know what?

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