Have found similar posts, but not identical. Here is situation:
1. Permalinks were set to Default.
2. Created WP site with pages and posts.
3. Changed Permalinks to date/name.
4. All pages and posts stop working
5. We get no error when saving the new Permalink format (choose radio button and saving)
A. New permalink for Page ABC = http://www.site.com/abc (confirmed in the Edit page)
B. http://www.site.com/abc results in a page not found.
Thank you in advance for your help and apologies if this was answered directly and I missed it.