Can't Get To Quizzes on Mobile

Once marking a unit complete, people are normally moved on to the quiz. On mobile though, the whole bar seems to be a link to "return to previous" rather than there being a separate link in the middle to take the quiz. So you know what page I'm referring to, I'll show you how the page is supposed to look on a computer: I'm getting reports from my customers that the whole bar takes them to the previous unit and they can't start quiz to move forward in the course. This is only happening on mobile. Any advice? Thanks.