Steps to reproduce:
1. Activate Staging
2. Create a page variation
3. Add a page to the page variation and publish it to live
4. Go to the Main Variation page and assert that the page is not shown (The page does exist on the Main Variation but it has to be enabled for it to be visible)
5. Navigate to Control Panel > Site Pages > Select Main Variation > click for tree view
You will notice that it says incomplete. (See attachment) It would be clearer if it was grayed out for example.