LEARNDASH LMS Course Builder Not Showing

Hey, i got the problem, well i download learndash LMS from this website, i really appreciate the hard work of null master. but i've encountered the issue for this plugin. Course Builder in course page doesnt work well or show a blank settings. its really frustrated. I've check general and global settings for builder and its turn on. So what i have to do to solved this problem. For notes my wordpress version is 5.2, help me . This is the screenshot of my builder