Hello,
Thank you for contacting the support, and sorry for any inconvenience that might have been caused due to that.
Make sure that this page was properly set to index so this can be included in your sitemap.
Classic Editor:

Gutenberg:

After doing so, please clear your sitemap cache and resubmit it to GSC.
Regarding your robots.txt issue, it is likely that you have a static robots.txt file present in your root directory. You may need to delete the file so you can edit your virtual robots.txt in Rank Math settings.
Hope that helps and please do not hesitate to let us know if you need our assistance with anything else.
Page is set to index in the rankmath page settings.
Nothing in robots.txt file: User-agent: * Allow: /
Cache has been cleared and page source still reads:
<meta name=”robots” content=”follow, noindex”/>
Root folder verified thru host.
Resubmitted sitemap. I’ll open a new support ticket later if issue persists. Thank you!
Hello,
Thank you for keeping in touch.
Let me know how it goes, Google may take a while to re-crawl your website.
If you don’t mind me asking, could you please leave us a review (if you haven’t already) on https://wordpress.org/support/plugin/seo-by-rank-math/reviews/#new-post about your overall experience with Rank Math? We appreciate your time and patience.
If you do have another question in the future, please feel free to create a new forum topic, and it will be our pleasure to assist you again.
Thank you.