Hi Kevin,
What do you mean by "2 other vCenter servers communicating with this one"? Is that Linked mode VCs since I think Linked mode VC is not supported.
I'm not sure why MHM is not working with the Standard license of the VC but try to uninstall MHM and
then install it with the VC that is in evaluation mode.
May sounds stupid but also make sure that the license(or Evaluation license) is not expired. You may also try to install on a single VC with Standard/Evaluation license.
hph,
Petko