If the meta box appears but all or part is blank, please see this article.
The Yoast SEO meta box can be disabled on the edit screen. This setting is retained when you switch between the same type of edit screen and when you log out.
Log in to your WordPress website. When you’re logged in, you will be in your ‘Dashboard’.
Go to the edit screen where the meta box is missing.
Click on ‘Screen Options’ in the upper right corner.
Check ‘Yoast SEO’ in the meta box.
If the edit screen does not show the Yoast SEO meta box option at all, the box has been disabled at the settings level.
Log in to your WordPress website. When you’re logged in, you will be in your ‘Dashboard’. On the left-hand side, you will see a menu. In that menu, click on ‘SEO’.
The ‘SEO’ settings will expand providing you additional options. If you don’t see the ‘Titles & Metas’ setting in your ‘SEO’ menu, please enable your advanced settings first.
Click on ‘Titles & Metas’.
Click on the Post Types or Taxonomy tab.
Posts and pages are listed under ‘Post Types’.
Toggle the switch to ‘Show’ for the type missing the meta box.
Categories and tags are under ‘Taxonomy’.