I have setup custom post type Courses, the slug is /course/, the attribute has_archive is not setup (uncheck).
I also created a normal page Courses (slug is /courses/) and a sub page Business (slug is /courses/business/).
Now the page Courses working good, but the page Business showing 404 error.
When I deactivated the ToolSet, the page Business works fine. I guess this problem is from the Toolset plugin.
Link to a page where the issue can be seen: hidden link hidden link
I just checked the same set up on my local test site and didn't encounter any problems, it worked as expected.
When I visit your site I can see that the /courses/ page works correctly. I can see that in the menu the business course points to the /courses/business/ URL which leads to a 404. But on the same page you have a link about business courses that points to /business/ (no courses prefix), and that works correctly.
Is the business page actually a child page of the courses page?
If it is and this isn't working, could you try re-saving your permalinks? Can you confirm on the business page that the permalink for the page is courses/business/ ?
If it is still not working, perhaps we could get credentials to your site to check the back-end for ourselves to see if we can spot the problem.
Let me mark your next reply as private so that we can get log-in credentials from you—you may want to create a temporary admin user for us to use that you can later delete. And be sure to have a current backup of your site.
