Had this happen on my YYZ-DXB flight before xmas. Tried the 3-2-1 reset thing and the SD also tried. Nothing worked and the J cabin was full. They brought me 2 extra blankets to try and help. SD filled out an on-board compensation form. I selected $ vs. Aeroplan points. Got an email the other day for a $1000 flight credit. I had the same thing happen on two of my NRT flights and didn't say anything as I thought there must be something wrong with me. How could it happen on this many flights. So mad at myself for not asking for the compensation form on-board.