Unable to edit page URL slug

Hi,

I am trying to edit the URL slug of one of my pages.

It is preventing me from saving the slug edit from:
setup-for-success-next-steps-2 to setup-for-success-next-steps

There is no other existing page with the slug setup-for-success-next-steps

Previously, I have had this error, and it has been because there is a piece of media with the same name, however a search in my media library revealed nothing.

Please let me know how I can change the URL slug.

Thanks.