Linkback link not generated under target post

Are there any conditions under which discourse does not generate a backward link under the a post linked by another post (I’ll call them linkback links)?

I’m not aware of any such conditions and so I’m wondering why the link (entitled “Filters just got a big upgrade”) at the very bottom of this post did not generate a linkback link under the target post.

Is it a bug?

It’s there now? Maybe they get added by sidekiq and it was behind?

No, I don’t think so. The link was added to the post more than two weeks ago.

But as I think about it: maybe it has to do with the source post being a wiki? Or the link in question being added in a later revision?