When I posted last, I noticed that the nice permalink took me to a 404 error page rather than my intended blog post. So I temporarily disabled the nice permalink until I could debug the problem.
After digging into it, it turned out that I was missing this stanza from my Apache configuration:
<Directory /var/www/wordpress/>
AllowOverride All
</Directory>
This meant that Apache was ignoring the .htaccess file that WordPress generated for permalinks.
Once I put that stanza in place, the permalinks started working again.
Many thanks to author of a DigitalOcean Community Tutorial for helping me solve this problem.
EDIT: Turns out, the post on LinkedIn was still returning a 404, since it wasn't prefixing the link with https://. Now I've setup a permanent redirect with:
Redirect permanent / https://jonathancamara.com/