My fifth round game at UniKL last Saturday. Both of us less than one minute left. I played Rc2 attacking his bishop and after his bishop moves, d3-d2 wins a piece. He kept thinking and thinking and after some time he moved Bd2-b4. I thought he must have lost on time, glanced at the clock and saw I actually was the one that lost on time! My opponent had just waited and pretending to think about his move until my time ran out.
I actually did press the clock but it did not register. This can happen if the table is uneven (because it is made of two joined tables) and your side is slightly lower. When you press, the clock just moved down due to the uneveness and the feedback made you think you correctly pressed the button but actually your time is still running.
This also happened to IM Mok Tze Meng earlier this year in Pahang. I was watching and wondering why he did not move as his time counted down.
By the way I do not blame my opponent, it is up to ourself to press the clock correctly and he has no obligation to point it out.