I would like to give you some idea how to find anomalies within your courses.
To be able to do that, you need access to your database and run some SQL reports. Probably the simplest way is to use the Configurable Reports block. I am not going to teach you how to use that block. I am not going to teach you how to write SQL scripts. But I am going to give you a few examples and the very basics, so if you have a bare minimal SQL knowledge and if you are not afraid to experiment, you will be fine. I am going to give you the SQL code with a brief explanation, so you can modify the code to match your own needs. Obviously I am going to start with a very simple one, don't worry.