Menu drop down not working

In the last couple weeks, the menu drop down has stopped working on ipad. I do not know about other devices. It works fine on a PC running windows. I have tried disabling all plugins to see if there is a conflict. No problem there. I then found it ONLY affected the menu items where the top entry is a blank with entries below. If I fill in something in the top menu bar listing it works. This used to work fine, but now does not. Any ideas?