When you click the 'Submit' button to report a player on the Bungie website nothing happens on your screen. I would expect some sort of 'Report Received' message but there is zero feedback (assuming there isn't some error I'm encountering). In my case I clicked Submit again and got a message about being patient and waiting a certain number of seconds, and it then popped me out of the reporting page. So I still don't know if the report went through or not. So I may have inadvertently reported the same player several times because I wasn't sure if it was working or not and I couldn't report them in-game because they left the match before it ended.