Now that this issue is to be passed to VMware engineering, I have decided to press ahead with our desktop migration to new compute without NVIDIA GRID, thus rendering this forum post otiose.
We will continue the support case and we may 'phase in' some Grid-enabled desktops as & when new members of staff join or there is a natural demand for the creation of new desktops, but as we cannot make it work with the existing desktops at this time, we accept defeat for our current deployment. If we ever find a solution, I'll post it here.
Thank you Sam @ VMware Support for giving this a go. Appreciate your time. An honourable mention for Rachel @ the NVidia forums who tried to be helpful.
I would like to thank the Community - but no one helped, so I won't.
I have had to bite my tongue and restrain myself from expressing my personal opinion as to how this experience reflects on the K1 GRID solution in its current incarnation.