Menu not showing on some content types
A couple places to start looking:


Block configuration

Is the menu placed as a block with specific logic that prevents it from appearing on certain pages. Go to 'Structure >> Blocks' and see if there is a block placed for your menu. Then under 'Visibility Settings'.
Context

Is the menu placed via Context? 'Structure >> Context', look for something that has to do with the menu.
Page Manager

Is the menu part of the page template or is it specifically placed in the content section of each page?  Check out a page that shows the menu and a page that doesn't in the page manager, go to 'content' of the applicable variant and see if you can spot any differences.


With out some more information it is hard to determine what method is being used to place the menu.