At this moment it seems that reporting in-game on Dead by Daylight is broken.
If you need to report someone for rule breaking (not because they killed you or teabagged you) you need to use The Player Report Form.
And no, there isn’t any notice anywhere about the in-game reporting being broken. There are no forum thread(s) or notice(s) in-game. And it would be nice if there were some notice about this somewhere!
The only source I can find for this is here, http://steamcommunity.com/app/381210/discussions/7/1693785669857844537/?tscn=1517384086#c1700541698680308230.