Hello,
Thank you for contacting Rank Math, and sorry for any inconvenience caused.
Please ensure that the Rank Math plugin is updated to the latest version.
https://rankmath.com/changelog/free/
Then, clear the Rank Math transients by going to Rank Math > Status & Tools > Database Tools > Remove transients

Once done, clear the website and browser cache and check again.
If the issue persists, check if you are using a Firewall, as there are chances that it will prevent saving the data. You can check this link for more information:
https://rankmath.com/kb/meta-data-not-saving/
I hope this helps. Looking forward to helping you.
Hola he realizado todo los que me comentaste y el problema persiste, pero he notado un error en consolo que me aparece cuando actualizo:
este me manda cuando empiezo a actualizar:
GET /wp-json/rankmath/v1/updateMeta/?_locale=user 404
y este otro cuando termina de actualizar:
Uncaught TypeError: Cannot read property ‘replace’ of undefined
at check.js:1
at Object.configure (check.js:1)
at post.php?post=141806&action=edit&classic-editor:5960
Hello,
Access to this file is getting blocked:
/wp-json/rankmath/v1/updateMeta?_locale=user
If you are using Cloudflare or any security plugin, you should whitelist the file in Cloudflare and Firewall, if that does not help I would recommend contacting your hosting support, to check if something is blocking access to that file.
Here is a guide you can follow to fix this issue:
https://rankmath.com/kb/meta-data-not-saving/#firewall
I hope this helps. Looking 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.