OS X El Capitan broke the Recent Items menu in the Dock. For example: Open a pdf or image in Preview. Right click the Preview icon in the Dock to access the Recent Items list. Is the file that is currently open in Preview available in the Recent Items list? In El Capitan and Sierra this list would only update after the app was quit and opened again. To make sure it's working correctly, compare the Recent Items list of the Preview icon in the Dock to the Open Recent Items list of the Mac menubar (Preview -> File -> Open Recent Items). Thanks in advance!