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.
You may need to enable the 404 Monitor module in Rank Math > Dashboard to see that option.

Please note that some options are only available when you enable the Advanced Mode in Rank Math. If it’s not showing, you must have chosen to use the Easy Mode. Please follow the steps in this link to switch to Advanced Mode:
https://rankmath.com/kb/advanced-mode/
I hope that helps. Thank you, and please don’t hesitate to contact us anytime if you need further assistance.
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.