How to troubleshoot why zathura doesn't follow web links?

I'm pretty sure that once I was able to 1. press f, 2. then enter a number, 3. finally hit Enter, and the link opened in the browser (I use [qutebrowser](https://github.com/qutebrowser/qutebrowser/)) . This doesn't seem to work anymore, in that following the procedure above, step 3. doesn't trigger any reaction in the browser, just like I've done nothing at all. Unfortunately, I don't know since when, so I'd like some help in troubleshooting it. On the other hand, in-document links are followed just fine, so I think that zathura simply doesn't know (anymore) what application to forward those links to. Fwiw, I use i3 as window manager, no desktop manager.