What does IPR mean on a grade report in Canada?
I am a former lecturer in Canada. As Nate has already answered, it (almost certainly) means In Progress.

I'll add (while this still falls under the "grades not yet available" scenario) that the student could see IPR for a course well after grades are normally available because they contested their grade and it's under review; some institutions may use a special notation for that (mine used GNA).

The professor may also have agreed to give the student an extension on some critical work to account for extenuating circumstances during the term, or delay the exam, while not forcing them to re-register in a following term.

My alma mater calls this IP, and it can be used for a myriad of other reasons:


  IP In Progress – a notation (IP) assigned to a course by a faculty
  member when:
  
  At the undergraduate level, an undergraduate thesis or
  course has not been completed by the end of the period of
  registration.
  
  At the graduate level, a graduate thesis, research
  essay, independent research project or comprehensive examination has
  not been completed by the end of the period of registration. The IP
  notation may also be used at the graduate level when a research
  seminar has not been completed by the end of the period of
  registration provided the research seminar has been approved by
  Graduate Faculty Board as being eligible for the use of this notation.
  
  In the case of re-registration in any of the above courses, the IP
  notation will remain; a final grade will normally be assigned in the
  final period of registration. Where there is no re-registration in any
  of the above courses, the IP notation must be replaced with an
  appropriate notation or grade within the prescribed time period, or be
  replaced by a notation of WDN.