Please I sincerely request you to check the support section : https://themeforest.net/item/wplms-learning-management-system/6780226/support
All support is provided via http://vibethemes.com/documentation/wplms/
Optionally : You can send me an email at vibethemes@gmail.com with subject “WPLMS Support”.
The response time for support forums is less than 24 hours, for emails is less than 72 hours. Support is off on Sundays.
Solution : Set the Course duration parameter from automatic to hours in WP Admin - WPLMS - Course manager.