2nd row of formatting menu missing in Safari

In Safari, when editing pages or posts, I can only see one row of the formatting menu. I can see the row that starts with the B and I buttons for bold and italic, but not the row that starts with a dropdown for headings/paragraph selection and then the U button for underline. Screenshot: https://imgur.com/a/ewzlO

For troubleshooting I have cleared the Safari cache, the cloudflare cache, and my caching plugin cache. I have switched to the 2015 theme and deactivated all plugins. I still get this issue.

Only in Safari. Not in Chrome. Latest OSX, latest WordPress version, all plugins and themes updated.

The site is https://www.smartnutrition.ca