vSphere 6 template issue

A couple of weeks ago I was on-site at a customer. While working I needed to copy a couple of templates from their current environment to their new environment. For all except one template this worked as expected. The one template had some actions grayed out.

To complete my work I needed first the Rename action and second Remove form Inventory, it looked like this could possibly be a issue.
My first thought was that the template had become orphaned for some reason, but this would result in having all actions grayed out. To verify if this template was still usable I deployed a VM from it, this worked without any issues. The deployed VM looked fine.
After this action I took another look at the available actions for the template and all actions were available again, apparently the deployment action "fixed" the issue.
The real cause and why deploying a VM from it fixed it is still not clear to me, but I guess the deployment does something to either the vCenter inventory or the database that clears up the issue.