There is no such code written in wplms.
however if user's order gets cancelled or refunded then we remove access from course .
This can happen if user creates two orders .
One got cancelled due to incomplete payment and other is approved .
Then for the cancelled order system removes access to course .
for this to stop please add this code in your wplms-customizer.php file wplms customizer plugin :
add_action('init','remove_cancel_order_course_check');
function remove_cancel_order_course_check(){
$obj = BP_Course_Action::init();
remove_action('woocommerce_order_status_cancelled',array($obj,'bp_course_disable_access'),10,1);
}
Please note that it will not fix the students who is removed ,you will need to add those students back again to course from course admin :
https://www.youtube.com/watch?v=GW_5rKKn1Us
It will work for future studnets creating orders .