I was editing an interview on one track, making clips. I dragged the clips out of the longer interview to the track below. When I went to play the first two, they played. But the third clip produced no sound. I had put focus on the clip, moved the start line to the right point for that clip on the second track, turned Solo on to see if that would affect it.....all to no effect. I then brought the original long clip into a third track, clipped out the problem segment (again), dragged just that segment to the second track row...and it played perfectly.
I noticed a similar question in 2013, never answered. Is this a peculiarity? Does one need to save before playing?