Hello,
Thank you for contacting the support and sorry for any inconvenience that might have been caused due to that.
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 logins 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,
I have updated the sensitive data as requested. Can you please check further?
Thank you.
Hello,
Can you please add the WordPress login URL in the sensitive data section?
We look forward to helping you.
Hello,
I have updated the sensitive data as requested. Can you please check further?
Thank you.
Hello,
I tried adding new keywords to one of your pages and it seems the keyword has been recorded.
Please refer to my video screencast in the Sensitive Data section.
Am I missing a step to replicate the issue? If the issue is only happening in a specific post/page, please share it here.
Looking forward to helping you.
Saludos, Efectivamente, ya había ingresado a algunas páginas la palabra clave, pero ahora por temas de SEO debo modificarla y no me sale la opcion para ello, no encuentro como modificar la palabra clave objetivo para cada pagina, tanto en las páginas que ya la había ingresado, como en las paginas que no la había ingresado, en definitiva no esta esa opcion del lápiz que aparecía en cada pagina para poder editar la palabra clave, y que antes si estaba sin ningún problema.
Hello,
I can check that the option to add keywords is working fine. You can access the meta box from the SEO tab:

Please clear the cache of your site & browser and check again. If the issue persists then please create a screencast of the issue using a tool like https://loom.com/ so we can check and assist you further.
We really look forward to helping you.
Thanks.
Saludos, cuando estoy en paginas no me da la opción de definir la palabra clave objetivo en la página, dejo captura en información delicada. gracias por su amable colaboración.
Hello,
The Bulk Edit option was disabled in WP Dashboard > Rank Math > Titles & Meta > Pages. I have enabled it and now you can edit the SEO details in the page list view:

Please check and let us know if you need any other assistance.
Thanks.
Si, ya se se soluciono, muchas gracias por su ayuda, el mejor plugin con los mejores colaboradores para ayudarnos a resolver inconvenientes como este. un abrazo.
Hello,
We are super happy that your issue is resolved. If you have any other questions in the future, know that we are here to help you.
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.