Try Utilities Menu > Update Layout. To avoid this, make sure Preferences > Edit has Automatic Update Layout checked on. Still, occasionally it's necessary to manually update.

Make sure you have not inadvertently added page breaks or blank pages in the Page Layout menu.

Thanks for all your help. I cured the problem by going into Preferences and removed "Systems Locks". See Bruce King suggestion.

A good book on Finale would help. The videos are excellent, but don't always identify your problem.