Hi @azurwebdesign
When you install Yoast SEO, in most cases, there’s no need to enter anything in the canonical URL field, as it should automatically self-canonicalize.
Often, we see problems occur in combination with another plugin or theme. The fastest way to rule out any conflict, is to deactivate all non-Yoast plugins and switch to a standard theme like Twenty Twenty.
Please test this on your development or staging site, if you have one. If not, we recommend using the Health Check & Troubleshooting plugin. This plugin has a troubleshooting mode, which does not affect normal visitors to your site.
If you’re unfamiliar with checking for conflicts, we’d like to point you to a step-by-step guide that will walk you through the process: How to check for plugin conflicts
With a default WP theme and only Yoast SEO as the plugin enabled, does the issue with the incorrect canonical URL appearing in the page source still occur?
If so, 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: this won’t actually erase your SEO data, which is also stored in WordPress’ default tables. It’ll just reset our index (custom tables) for that data.
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 installing, updating or removing plugins. Learn more about the benefits of regular backups.
Can you check if this then resolves the issue?
