Hey,
When user clicks the enroll course button the ajax is loading... forever, and nothing happens. After reloading the page several times the student is enrolled and when he clicks the start course button appears an error page.
Please make sure that your wplms theme and all its plugins are updated to latest version .
Also if you are using wplms batches plugin then please make sure that your batches plugin is updated to latest .
If already updated to latest then ,Please share your site url and admin credentials to check this issue at your end .
PS : mark reply as private while sharing .
Make sure that "activity streams " component is enabled in your wp-admin -> settings -> buddypress -> components .