Coursepress Pro error

Hi,

Updated the plugin today and I notices this error on the course page. http://education.telemedicophysicians.com/courses/cardiology-education-level-one/

Warning: array_filter() expects parameter 1 to be array, boolean given in /home/content/a2pewpnas01_data02/68/3954768/html/wp-content/plugins/coursepress/2.0/include/coursepress/data/class-student.php on line 2004