Anyone actually querying a TKB by Product Category Successfully?

In my staging environment, I am trying to write a component that processes the following LIQL query:

SELECT subject,view_href FROM messages WHERE board.id = 'MyBoard@tkb' AND product_category.id = 'MyCategory' AND products.includes = true ORDER by metrics.views DESC LIMIT 5

This example is directly from the documentation, with my goal to get the top viewed assets in a given product category.
This query, however, returns zero results.

If I query for messages for a specific product like the following, I get results:

SELECT subject,view_href FROM messages WHERE board.id = 'MyBoard@tkb' AND products.id = 'TheProduct' ORDER by metrics.views DESC LIMIT 5

If I query the products in the product category ID 'MyCategory' I get the expected list of products.

SELECT id FROM products WHERE product_categories.id = 'MyCategory'

Anyone else doing this successfully?
Unfortunately, I've had a support ticket on this open for a few months with no movement or resolution.