Is anyone else having this problem with Sonar Pro X3d ? When I use Bounce to Tracks or Export to Audio,the initial transient is always missing...EG : In an intro or a count in,the first part of the first beat is missing...This feature worked fine in all Sonar X1 and X2 but there seems to be a problem in X3d...It would be nice if this problem was fixed because the initial transient is usually quite important in the scheme of things 

I have seen that at times, but not sure the reason why (is always a MIDI note that doesn't "take" when it does happen, so may be the "note on" data is actually not there). My work around has been something I have carried forward from 15 years ago, which is to pad the front of projects with a bar of silence.
 
If bounce to a final track, you can then tailor that lead-in to your liking before export.

Not sure if this has anything to do with it as I don't know whether you are using a drum editor and I think this usually applies to the end of songs BUT if you are using something like BFD for drums be sure to set the sequencer to Offline otherwise notes and tails can get cut off when bouncing.
 
If this is just audio maybe drag out the start of your clips so there is a lead in before the audio starts. This might fix it because the computer is already mixing down by the time the first transient hits. Then trim it after the fact in a new project or in something like Pyro.
 
Also try disabling Fast Bounce in the Export options. That can sometimes make things go wonky.

Oh and maybe if it is a midi note being missed at the beginning try freezing the MIDI track(s) which takes the synth completely out of the equation and/or inserting a single note a measure before the song starts (part of the lead in I was referring to earlier) so that way it triggers the synth making it active before the song starts instead of it jumping to life at the last second.
 
Just some general ideas to shake loose that first note. Hopefully one of these solutions help pin down the problem.
 
What synths/sequencers are you using (if any)? Might be a known issue that others have encountered with that specific plug.
 

Thanks for the replies guys...The problem is to do with audio rendering - bounce to tracks or export to audio,but I'll try it with MIDI..This is a problem that has appeared in Sonar Pro X3d x 64...I filed a report with Cakewalk and they have told me that it is a system error on my part and have closed the case...That's not a very satisfactory outcome as far as I am concerned,because this problem was not present using X2d with the same hardware..I still believe that there is a problem in Sonar X3d and it would be nice to get it fixed....

If you're selecting the audio, make sure the selection isn't snapping to zero crossings. I've had situations where I've missed the beginning of an audio file because the selection snapped to a zero crossing that occurred after the initial transient.
 
Sonar defaults to snapping to zero crossings so unless you've de-selected it, it's selected.

Thanks for the reply Craig..I turned off the zero crossings option,but the problem still remains...The initial transient is still missing in bounce to tracks and export to audio...I have been a Cakewalk user since the stone age and like I said before,this problem has only appeared since I upgraded to Sonar Pro X3d...I do believe that there is a problem in the software,but the techs are telling me that it is my hardware   

I'm grasping at straws here, but try with and without PDC enabled. Maybe even try different latencies.
 
Also, are you using fast bounce or real-time? And is any external hardware involved, like a UAD card?