My RCIC advised me to apply for my PGWP while I was on maintained status as a student. My study permit was set to expire before the end of my studies, so I applied to extend it before the expiration. My RCIC said I would be able to work, but it seems like they were wrong. You cannot work if you apply for your PGWP while on maintained status as a student.
I just received my study permit extension approval yesterday, so I now have a non-expired study permit. If I withdraw and resubmit the PWGP application, I should be able to work full time while the application is in progress.