404 after changing default landing page permalink prefix

After changing the permalink structure, try heading into the permalinks page to manually flush the permalink cache.

By simply going to the permalinks page it should reset the url structure and fix the 404.

Let me know if this isn’t the case

Here is additional information on solving 404 issues: https://www.inboundnow.com/landing-pages/docs/users/faq/fixing-landing-page-404-error/

Let us know if you still are having issues.