Primary menu, custom CSS, fonts, and favicon not working

I originally posted this in the wordpress.com forum, but was told to do it here instead because the blog is self-hosted.

I’m using the Plane Theme from wordpress.com for my fiancée’s blog at https://www.putyourfoodtowork.com.

I noticed that the following things are no longer working:

• Primary navigation menu, which is normally at the top of the page has disappeared, even though it’s still setup properly in the customizing > menus section
• Custom CSS

Here’s the CSS for reference:

.site-title {
	font-size: 3.25em;
	text-transform: none;
}

.site-description {
	color: #efefef;
}

a {
	color: #0645AD;
}

.site-info {
	display: none;
}

• The Heading 1 font should be Pacifico since it’s selected in the customizing > typography > default typography section. The weird thing is I can change it back to the theme default, save, and then change to Pacifico and it works. But once I change something else or reload the page it goes back to the theme default.
• Lastly, the favicon is showing when logged in as admin, but it doesn’t show up when viewing the blog when logged out or in incognito mode.

I’m guessing all this weirdness is due to an update not playing nice or something like that. Any help would be greatly appreciated!