Referencing a GHES-hosted action (from GHES!)?

Hi folk,

My organization self-hosts GitHub Enterprise Server 3.0.9 with Actions enabled. It is easy enough to reference any action hosted on (if it’s a public repo). What I would like to do is create a repo within my enterprise organization and then reference it from a workflow within my GHES instance. Currently, I find that any attempts to reference an action will fail (“repository not found”).

I may be able to escalate this through our support package, but I’m curious if anybody knows any magic off-hand.