mobile menu does not show on mobiles!

Have been using this plugin for quite some time and lately the mobile menu just refuses to show on mobile phones! It shows on tablets but not the phones. I can only assume that the breakpoints are somehow incorrect. Site I am using it on is coolwebs.com.au (badly needs an update I know…)

Not sure if it is the plugin, wordpress core or something wrong with my site. May consider doing the responsive menu myself in a new theme and dropping the plugin.

Thanks for your hard work though.