When the practice performance charts get loaded, the status that you get is combined for all the subjects in your course.
You should look at subject-wise status also to ensure that no subject is ignored. To get the status of any subject, click on the subject tab. You can get Practice Status, Difficulty Level Wise Status, Period-Wise Performance and Knowledge Index for every subject. You can interpret the respective charts as per the instructions for respective performance charts (for all subjects).