It is not working at all here to me. Even in Chrome. Also i couldn’t find any js error. So i am yet unknown why this is not working in first load. So to test this, can you please change your theme with wordpress default theme ? May be there some conflict in theme and it is blocking it. Also, please try deactivating other plugins and see if this works.
Once you find out what is causing it, please kindly let me know i will investigate it further.