drop-down menus: open vs. closed state by default

[Misk1]

I recently implemented drop-down menus as shown in this how-to: https://help.shopify.com/manual/sell-online/online-store/menus-and-links#create-a-drop-down-menu

Works great on desktop and tablet on my responsive theme, menu appears with a link to each of my collections. Perfect. 

When viewing the responsive site on a mobile phone, however, the drop-down menu appears open by default instead of closed. This is problematic because as the list of collections grows, it pushes all the other navigational elements way down the page, below the fold. 

I'd like for the mobile to mimic the behavior of desktop and tablet, spitting out the list of collections in the drop-down only when clicked. 

Is there any way to set the default state of the menu to be "closed", until the user clicks it? 

This is the theme i use https://elements.envato.com/moltestore-multi-store-responsive-shopify-theme-VEZ73BE

This just started today, before that the menu worked fine. I don't really know why it suddenly started.