Sub Menus at mobile devices need a Parent Placeholder to open the Child Menus. Try to change the logical structure of your menu. It might be,
– Parent Title e.g. Our Productions – You can set the link to “#”
– Chile Menus e.g – Productions List, Kids Travel Thailand, Kids Travel Vitenam etc
This may resolve your issue.
PS: I have forwarded this ticket to our Responsive Engineer to look into this matter.