Blog entry titles not showing in lists in 3.7

In the ‘blog view’ (the main page at https://www.evildrganymede.net ) all the titles for my blog entries have vanished since I updated to 3.7. There’s a ‘permalink’ that just looks like (0) at the bottom of each post, but it’s now hard to see where one article ends and the next starts.

This also seems to happen in views that list multiple articles (e.g. https://evildrganymede.net/category/rpgs/2300ad/ )

But if I am looking at the article directly (by clicking that (0) link at the bottom of each post) then I can see the title fine (e.g. https://evildrganymede.net/2013/10/16/2300ad-realistic-star-map-project-part-v-the-new-chinese-arm/ )

Anyone else having a similar issue? I can’t find any setting that would have randomly just turned off all the blog titles. I’ve never had this issue before with any updates (I’m using the K2 theme) and I would like to get the titles to be visible again on the lists.