I create a VM using OXC, then start it up. I therefore open the Citrix-provided XenCenter, and I see the running machine not associated to the XenServer machine hosting it; I see beside the stopped ones.
I've try to dump all the parameters using xe vm-param-list, and I see that the OXC-created one has 2 more properties that doesn't show up in the XenCenter-created machines.
One of them is "default_template".
I delete the parameter using "xe vm-param-remove param-name=other-config param-key=default_template uuid=<uuid-of-the-machine>" and the machine now shows correctly in XenCenter