There is currently an issue that can cause a break in the connection between iClicker and Canvas.
The issue occurs if an instructor has clicked the Sync Roster button since this weekend (10/28-10/29) which can cause students to show as unregistered.
Canvas is working to correct the issue, and ask that anyone experiencing the issue email support@iclicker.com and CC kelly.morrow@macmillan.com and they will help resolve the issue.