It's visible to administrators but not members it seems, though settings seem to show it should be available to all.
Let's say that you've all posted too many times on that specific thread, and the forum is throwing a tantrum!

In all seriousness, I'll look into it now - though on the surface, it appears fine! Should I fail to do anything, Liam will be on it. He may not be able to do anything until tomorrow though.

Sorry for any inconvenience caused - we hope to have the issue rectified as soon as possible.