The sound will still play. But sometimes I hear the ping so I decide to check who is trading me. But all the trade icons disappear and nothing appears on the side to accept or decline, or who even traded with me!
It tells me who declined the offer when they cancel it. But I thought I'd let you guys know since its not something that happens often but I do encounter it every now and again.
Is there something you really can't do without in the client? Is Udyr displaying as a Picasso painting again? This is the place to report bugs and give suggestions for League of Legends in general!
Don't spam your suggestions or bug reports here, and follow the [Universal Rules](http://boards.euw.leagueoflegends.com/en/c/announcements-en/3eWpXbJi). While not every suggestion here will be implemented, your favourites can be voted to the top for maximum visibility!