NoIndex Issue with Category Pages

@kknollseo That setting only sets the default for category pages. You can also override that on the particular category in the Yoast meta box. Can you please check this setting by performing the following steps:

In WordPress, go to Posts>Categories
Go to the edit screen for the Category
Scroll to the Yoast meta box
Under the Advanced area, check the setting for ‘Show in search results’ is set to ‘No’
Click ‘Update’

Can you please try the aforementioned suggestions and let us know whether this resolves your issue?

Thanks for your confirmation and for sharing the relevant screenshots with us. The issue you’re currently experiencing is very odd as the screenshots you’ve shared with us show the correct settings. So, Yoast SEO should output the noindex robots meta correctly as expected.

That said, to see what’s going on, we’d like you to please perform a conflict check at this point. This will help us narrow down the exact cause and determine what the next steps are while saving you time.

The fastest way to do this is to deactivate all non-Yoast plugins and switch to a standard theme like Twenty Nineteen. 

Test this on your development or staging site, if you have one. If not, we recommend using the Health Check & Troubleshooting plugin. This plugin allows you to run a conflict check without affecting normal visitors to your site.

As we can imagine that 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.

If you do not feel comfortable doing this yourself or if this does not solve your issue, our Yoast SEO Premium plugin comes with one year of (technical) support.