It seems that the summary is only based on the first line of post source, so when a link uses a "named" link, it fails.
Go back to the post listing and look at the summary to see this bug in action.
This is an unfortunate consequence of a performance feature of markdown-it, which provides a `renderInline` function to do *almost* exactly what we want for answer summaries.
I did raise it as [an issue on GitHub](https://github.com/markdown-it/markdown-it/issues/615) but it isn't going to change:
> References are not "inline" objects. So, works as expected.
We are left with three choices:
1. Edit answers so the first line only has inline links.
*Downside:* we'll probably be forever editing posts just for this tweak, and it makes posts that have neat links less neat.
1. Use the full-fat renderer for generating the answer summaries.
*Downside:* we've tried this, and apart from meaning a lot of unnecessary bandwidth downloading full answers to the client, it also appears to be hard to get right.
1. Pre-parse reference links in markdown on the server.
*Downside:* this will get horribly complicated and bug-prone if we try to do too much — we can probably get away with just replacing reference links.
We've gone for option (3) for now at least. Reference links were the last *common* oddity showing up in the answer summaries, and now they work, along with all the genuine inline markdown. Performance and bandwidth aren't affected because we generate the amended markdown one-liner when answers are posted or amended, and only send that snippet to the browser where it needs to render answer summaries.
[This fails] ₋ [This works](#) — This answer is just to demonstrate the bug.
[This fails]: #