After much trial and error, found the culprit… an errant quotation mark hidden in a CSS element.

Thanks, that resolved it, but please add my request to add such settings to admin or to include file in child theme.

Site is http://www.snapchops.com/.

Attempting to use the Category Filter in block settings. As you can see on the screen capture, the Category Filter dropdown only shows categories up to the R’s — there are many more after that.

Thanks for the input, but good news… I found a plugin that works perfectly:
Ultimate Category Excluder

By the way, I directed the same question to Themify and received the following response:

Thank you for reaching out to us.

That’s very odd. All our plugins are constantly updated to ensure that it will work with the latest WordPress framework. Do you mind checking to see if the NewsMag theme is updated with the latest WP framework? It shouldn’t break the CSS.

Let us know how it goes.

Regards,
Kurt
Themify Team

W: themify.me
E: info@themify.me

I’ve got the same issue. Is there a resolution for this yet?