Quiz button "next " isn't working.

Quiz button “next” isn’t working in the last update 0.9.18 and in the update 0.9.17. So, the option “next” isn’t shown but i reload browser(F5) is shown.
I saw the problem in the code, but i can’t fix. I explain
For example:

<?php $question_id = !empty( $_REQUEST['question'] ) ? $_REQUEST['question'] : 0;?>
<?php if( $next = learn_press_get_user_next_question_url( get_the_ID(), $question_id ) ){?>
        <button type="button" data-nav="next" class="next-question" data-url="<?php echo $next;?>"><?php echo apply_filters( 'learn_press_quiz_question_nav_button_next_title', __( 'Next', 'learn_press' ) );?></button>
    <?php }?>

This is the code next button. When the quiz is starting ,”$question_id” always is empty but i reload browser “$question_id” is not empy and so “next” button is shown.

$question_id should have the id $_REQUEST[‘question’] the first time the quiz starting.
How can i fix it?

Thanks a lot in advance.

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