I am using a Child Theme of Twenty Thirteen for my site.
I have set the site to appear the same whether on desktop or mobile (basically non-responsive).
On iPhone, Submenus are visible, yet clicking on them does not work. Holding down a submenu item will prompt a "open page / open in new window" dialog, which will sometimes go or not go to that page.
I've disabled plugins to troubleshoot. The only thing I can think of is that I disabled the Viewport tag in the header.php, and again I don't want the responsive menu.
If someone knows of a fix, please help. My site is not live yet - I can provide a temp login if needed to view the site.