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.
Could you please ensure that you are not using the same slug for posts and categories when the Strip category base option is enabled?
Please also share some affected URLs to check. You can add it in the sensitive data section

It is completely secure, and only our support staff has access to that section.
Looking forward to helping you.
Thank you.
Hello,
I have updated the sensitive data as requested. Can you please check further?
Thank you.
Hello,
Sure, we can take a look at your site. Please edit the first post on this ticket and include your WordPress & FTP 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/
We really look forward to helping you.
Thank you.
Hello,
I have updated the sensitive data as requested. Can you please check further?
Thank you.
Hello,
Could you please verify the credentials? It looks like the one you mentioned aren’t working.
Here is the screenshot for your reference:
https://i.rankmath.com/uQx7KS
Looking forward to helping you. Thank you.
Hello
I solve the problem. Thank you.
Hello,
I am glad that the issue is now resolved.
Do let us know if you have any further questions.
Looking forward to helping you.