Hello,
Thank you for contacting Rank Math and sorry for any inconvenience that might have been caused due to that.
Please Make sure you have enabled the SEO controls both for page and post, then it will appear on the pages as well as posts.
To enable SEO controls for pages Go to the WordPress Dashboard > Rank Math > Titles & Meta > Post Types tab > Pages and for Posts go to the WordPress Dashboard > Rank Math > Titles & Meta > Post Types tab > Posts, then scroll down, you will find the Add SEO controls option in both section. From there just enable the option.

Hope this helps. Please do not hesitate, if you face any issue. We are here to assist you again.
Thank you.
Hello and thanks for the reply; both options were already on, I deactivate and reactivate them, but nothing yet.
I can see the Rank Math SEO tab at the bottom, but it’s not showing anything
Hello,
Thank you for getting in touch with us.
Can you share which editor you are using?
Assuming that you are in the Classic Editor as SEO Controls are available at the bottom of Classic Editor. So please make sure you have clicked the “Arrow Sign”. Then the SEO Control will appear.

Hope this will help you. Looking forward to helping you.
Thank you.
I’m using the classic editor and of course I’ve clicked on the arrow sign. Look at the screenshot, maybe it can be helpful
https://ibb.co/YW4nqJY
Hello,
This is likely to be a plugin/theme conflict with Rank Math’s metabox.
Assuming you are using the latest version of all the plugins and the themes (please update if not yet), it would seem like a conflict with one of the plugins or the theme you are using.
To determine that, please follow this troubleshooting guide:
https://rankmath.com/kb/check-plugin-conflicts/
Here is a video you can follow as well: https://www.youtube.com/watch?v=FcIWRhcUP2c
Only the site admin would know and your users won’t be affected by this troubleshooting.
If the issue persists, please edit the first post on this ticket and include your WordPress login in the designated Sensitive Data section.
Please do take a complete backup of your website before sharing the information with us.

It is completely secure and only our support staff has access to that section. If you want, you can use the below plugin to generate a temporary login URL to your website and share that with us instead:
https://wordpress.org/plugins/temporary-login-without-password/
You can use the above plugin in conjunction with the WP Security Audit Log to monitor what changes our staff might make on your website (if any):
https://wordpress.org/plugins/wp-security-audit-log/
Please do take a complete backup of your website before sharing the information with us.
We really look forward to helping you.
Hello,
Since we did not hear back from you for 15 days, we are assuming that you found the solution. We are closing this support ticket.
If you still need assistance or any other help, please feel free to open a new support ticket, and we will be more than happy to assist.
Thank you.