Outline/navigation problem

When I try to navigate using the outline option in 4.05, only a limited range of the headings are available and I cannot scroll down the list to reach those further down the document. I can only about a third of the headings in the document. The problem is not the level of headings that I have ticked in the settings for the outline but the number of headings that I am able to see in the navigation list.

All working fine now.