When the screen containing the website is made smaller and the primary menu on top of the website is crammed together, not so narrow that the menu disappears, the drop-down submenus don’t show the pages they are supposed to show.
Instead, I just see the same colour as my background dropping down.
This is only the case when the screen is narrow.
( Browser: firefox)

On the image: there should be two more submenus on the drop-down menu.
Website: www.arizonatype.com