Bug: Filter by provider isn't working in my books

[bibliothecary]

Description of your request or bug report:

@NihongoLearner19

The “filter by provider” function isn’t working for me. I’ve added the Google Play and Ridibooks links to a few books myself, so I know they’re listed on the book pages. However, when I try to filter by provider (either Ridibooks or Google Play) in my library, it doesn’t work. The list of books stays the same.

Trello link: