Drag & drop system doesn’t work ad expected

Thanks for your free plugin “Course Scheduler for LearnDash”.

I found some issues with it. I’m reporting to you, hoping in a quick solution:
1. the Dashboard panel is empty and some errors are displayed in console: wn-dashboard.ccs and wn-dashboard.js resources aren’t load;
2. on the Calendar panel, when I try to drag & drop a course on the calendar, it is displayed on the day but it seems not to be saved correctly: some errors on fullcalendar-init.js are generated;
3. on the Calendar panel, when I use the arrows to go back and forth by months, course on the calendar are displayed twice;
4. on the Calendar panel, when I reload the page, sometimes courses on some calendar days disappear (they’re not saved correctly).
5. on the page course (front-end) I can see the days of course availability but the course isn’t available on those days.

I think there are some issues with the JS and the drag & drop system on the backend.
Please, can you check it?