I didn't miss anything. Go have a look at the OWP form, IMM5710. It's called Application to Change Conditions, Extend my Stay or Remain in Canada as a Worker.
She had status as a student and applied to change her status to a worker. Her study permit is no longer valid and she is studying illegally.
It is stated in the guide.
Can my spouse or partner study in Canada?
If your spouse or common-law partner already has a study permit and wants to keep their temporary resident status as a student, they may submit an Application to Change Conditions, Extend my Stay or Remain in Canada as a Student form [IMM 5709] (PDF, 488.83KB).
She can apply to change her status back to student. Any studying done in the meantime will still be illegal.