Hello,
Thank you for contacting Rank Math, and sorry for any inconvenience caused.
The changes made to the author slug in the meta box will not work because WordPress doesn’t allow to change the author slug by default.
Please use the following plugin to make changes to the author slug: https://wordpress.org/plugins/edit-author-slug/
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.