I am not sure if this is the same issue, but just yesterday I was using LP6.4.2 and I hit the BOUNCE and ADD button. It played through with the bounce window showing progress. Then nothing was there. Nothing on the audio page and nothing when I did a file search. So I figured I must have done something wrong and did it again. Same thing. Three times. Finally on the fourth attempt did Logic deem it necessary to actually create the file. Got a couple more "Try to Save Your Songs"'s too. Great that they got al the bugs out.