'System Message'/Header function gone in 11.2?

I’m running gitlab-ee. I’ve recently updated to 11.2, and the System messages (this feature) that I had configured have disappeared. I’ve managed to kind-of reinstate them using broadcast messages, but that doesn’t seem to be quite the same.

I’ve examined the changelog and can’t seem to find anything that references any particular change.

Perhaps (here’s hoping) it’s just moved, and I can’t find it anymore…

Any ideas?