There are a few different things that could contribute to this; the first is sometimes we see this happening if a student is using a loaner device. Because so many user profiles are loaded onto the loaner over time, the GoGuardian extension is not able to properly initialize. The other possible factor is that the chromebook they are using did not properly enroll itself.

First, ask the student to perform a hardware reset on their device. If the student still does not appear in GoGuardian, submit a Help Desk ticket. We will be able to remotely reset the device.