Hi,
Can you confirm you are using the most recent Yoast SEO v5.7.1??You can learn more about updating here: https://kb.yoast.com/kb/how-can-i-update-my-free-plugin/
If the issue still happens, that sounds like a plugin or theme conflict. Can you try and gather as much information for us as possible? Please perform the following:
1. Make sure the issue doesn’t persist when Yoast SEO is disabled.
?2. Check for conflicts using this guide: https://kb.yoast.com/kb/how-to-check-for-plugin-conflicts?
3. Check for JavaScript errors with your console with this guide: https://kb.yoast.com/kb/how-to-find-javascript-errors-with-your-browsers-console
If you find any JavaScript errors related to Yoast SEO or if there is a conflict with a plugin or a theme, you can create a new GitHub issue here: https://github.com/Yoast/wordpress-seo/issues/ for our developers. Please report the issue to a third party developer as well.
If you didn’t find any conflicts or errors, we think the issue is specific to your site. We’d need to investigate further but are unable to do so on these forums. You can purchase Yoast SEO Premium here: https://yoast.com/wordpress/plugins/seo/ and receive our Premium email support and we can help you further.
