Tournament.get_final_ranking() appears to not work

[monospacedmagic]

  File "/home/luci/Purah-Cogs/tournaments/tournaments.py", line 889, in end_to
urnament                                                                        
    ranking = await tournament.get_final_ranking()  # type: dict                
  File "/home/luci/purahenv/lib/python3.7/site-packages/challonge/tournament.p
y", line 783, in get_final_ranking                                              
    return OrderedDict(sorted(ranking.items(), key=lambda t: t[0]))             
TypeError: '<' not supported between instances of 'NoneType' and 'int'

No clue what I'm doing wrong. This is after I called Tournament.finalize(), and it worked (and I ignored the challonge.APIException, see #5 for details on that), and I made sure it worked by checking on Challonge.

[fp12]

Does it happen every time? It seems to run fine on my tests so far...