Hello,
Thank you for contacting Rank Math and bringing your concern to our attention. I’m sorry for any inconvenience this issue may have caused you.
For initial troubleshooting, please ensure that the Rank Math Redrection tables are created on your site.
Head over to Rank Math > Status & Tools > Database Tools and recreate the Rank Math tables by clicking this button:
https://rankmath.com/kb/rank-math-status-and-tools/#recreate-missing-database-tools
Once done, clear your website’s cache and try adding redirects.
Let us know how this goes.
Thank you.
