The Roll Call cannot track a student's attendance across multiple sections within the same Canvas course. This shortcoming may negatively impact instructors with large courses and multiple sections, such as lecture, labs, and discussions.
Roll Call is able to track attendance of students within only one section of a Canvas course. Therefore, in Canvas courses where students are listed in both a lecture section, and a discussion or lab session, Roll Call will not work as most instructors expect. Instead, Roll Call will track attendance for a particular student in either the lecture section, or the discussion/lab section, but not both. It will display a grade based on the most recent attendance change made, regardless of section. Roll Call will not inform you of this; it will simply present in the gradebook the attendance grade for whichever section was most recently updated. So, students may see their attendance grade fluctuate (seemingly) irrationally.
At present, there are no known workarounds for this limitation with Roll Call.