Hello Jennifinch,
Thanks for reaching out regarding your canonical URLs. And you are correct; the Yoast SEO plugin uses self-referencing canonical. So /blog/ and /blog/page/2 should reference to themselves respectively.
However, since this is not the case for you, can you please try resetting our indexables in the database tables by following the steps below?
1. Install & activate the?Yoast Test Helper plugin
2. Go to Tools > Yoast Test
3. Locate the Yoast SEO section and click on the ‘Reset indexables tables & migrations’, ‘Reset Prominent words calculation’, and ‘Reset Internal link counter’ buttons. After each click, the page will reload to confirm that each reset was successful. Note: Resetting the optimization doesn’t undo any of the hard work you’ve put into the plugin as the SEO data is also stored in WordPress’ default tables. It’ll just reset the custom Yoast tables that contain the combined data pulled from those default tables.
4. Go to SEO > Tools, and under SEO data, click the “Start SEO data optimization” button to allow Yoast to rescan your?content.
For your site’s health and safety, we recommend creating regular backups of your site and database. This is especially important before making important changes on your website. Learn more about the benefits of regular backups.`