Hello,
Thank you for contacting Rank Math and sorry for any inconvenience that might have been caused due to that.
These stop words will be removed when they exist on new posts and page titles when auto generating the permalink. I have tested this on my end and it works smoothly.
If you can replicate this issue when creating new posts, then it is possible that one of your installed plugins is also modifying permalinks and you might need to run a conflict test to identify the culprit.
Please follow the steps on this page: https://rankmath.com/kb/check-plugin-conflicts/
Looking forward to helping you. Thank 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.