There are a few points to be taken into consideration:
1 - Was the student enrolled in that course?
2 - When was the course created?
If the course was created by you today itself, and if you had kept the default settings for the course, then the 'Course start date' is by default set to the next day. In this case, the course will appear in the students dashboard in the 'Course overview' block-> 'Courses' tab -> 'Future' section and will appear in the 'In progress' (which is the default view in dashboard) section on the next day.
You can check the 'Course start date' in the course settings.
3 - Course visibility
Check your course setting for 'Course visibility'. It should be set to 'Show'.
Let me know if there are any further queries other than this.