Category pages blank, but shop works on WooCommerce on WordPress

At some point, we don’t know when, category pages stopped showing anything other than the header/footer of the page. This isn’t for just one category, but all categories and sub-categories.

The main store page, and products, display fine. For example, this is a product page.
https://thesmartspacer.com/product/conference/

But, when you click on one of the categories in the breadcrumb path, you get a blank page.

Similarly, if you click on any category at:
https://thesmartspacer.com/product-category/
Nothing comes up — blank page (except header/footer).

Even categories with only products in them (e.g., no subcategories), same result:
https://thesmartspacer.com/product-category/uses-and-applications/banquet-and-events/

I’ve tried disabling all the plugins that were added at any point in recent history … or that I suspected could impact categories, including Yoast and Yoast Premium. But, pages category and subcategory pages are still blank.

Ideas? I’m just baffled and if I cannot figure this out, I’m going to need to cleanse the site of categories so it’s functional … which is drastic, and I don’t want to go there.

Help!

Thanks!
Neil