Cannot report player retroactively

[Sir Gamer]

There's no "report" button in the match history in the player's profile, although all the needed information (match id, player id) should be there.

Had to leave a match due to a leaver in my team and a cheater in my lane. Checked my profile after another (complete) game, the match was not there. Checked my profile today, the match is there but the report button is missing. Ugh.

 

[sickboy]

I don't know how we're supposed to do this, since they removed the "R" button from the end screen. There were a whole bunch of comments saying you could do that from the match history a month ago, but that doesn't appear to be the case anymore.
Please fix this oversight, or let us know how we're supposed to do this.