Maybe I'm being stupid and missing something obvious.
I'm trying to delegate access to a set of VM's via the Roles menu in Enterprise Manager.
I can add Protection Groups for physical machines just fine, but when I try to select any of my Hyper-V VM's, I just get a blank list, show below;

I read the Veeam documentation pertaining to reverse DNS being in place - I've ensured that is the case, and records for all of my VBR servers (including the BEM server) are in functioning correctly.
As far as my VM's go, they're in 2 Hyper-V clusters, and appear like this in each regional VBR server;

I've not seen any other topics on this, so maybe I'm just doing something silly!