Google web fonts not working on Live site, but working in Customizer

I have a problem that appears to be similar to the one described in this thread:

google web fonts not working

Basically, I can see web fonts fine in the Customizer tool, but when I save the changes and view the Live version of the site, the font has defaulted to a generic sans-serif font that is different from the font I chose.

I have checked on the server in the wp-content directory and there is no advanced-cache.php file to delete. I am only running SiteOrigin plugins (Page Builder, CSS and Widgets Bundle). I also tested it with all of these plugins deactivated, and the same behavior occurred. I’m not sure what I should try to get web fonts to behave correctly.

Update 1:
The URL of the site is http://www.ectropyarts.com/

Details font should be “Allerta Stencil” (I’m just using something distinct for troubleshooting purposes, so that it should be obvious if I find something that fixes the issue).

Update 2:
I found another bit of interesting behavior. If I select a “Main font” instead of leaving it blank, it appears that all webfonts (Details font, Main font, and Headings font) work. This may be a potential workaround, but there does still appear to be a bug when you try to select a Details font or a Headings font alone (without a Main font).