Steps to replicate:

1. Enable CamelCase links.
2. Create a CamelCase link to a page that doesn't exist, and save the page.
3. Disable CamelCase links.
4. Check "Undefined Pages" in Browse Space, and the CamelCase dead link still exists (even though it's not shown on the page).

Is it possible that Confluence is determining "Undefined Pages" when each page is saved, not on-the-fly when the user checks the "Undefined Pages" page? If so, there could be other associated bugs.