Variable value in 'insert equation' not displayed in formula question quiz

[cjudge]

When I create a formula question in a Canvas quiz and I define a variable within the latex environment (i.e. 'insert equation') then the numerical value of the variable will not display for those who take the quiz.  

For example, if the question is `Find  \int_0^{ [a] } x^2 dx'  then `a' becomes a variable. And Canvas recognizes this variable. But when the quiz is previewed, the value of the variable is not displayed. 

Is there any quick fix for this, or is it just a bug that will be around for awhile?