When I record my midi file to audio file, no problem.  But when I want to export to a wave file it works some times in a row then quits exporting. I've tried changing from wave to Microsoft's wave file and it works some of the time.  Now if I reboot and start over it will work fine for a few more times and then quit exporting properly.
I am using Sonar 64 bit on a Window 10 64 bit.  It does show a show a glimmer of the black bar converting in Sonar, but when I click on Windows player it will sometimes give a small piece of the file then dead.  Most of the time it just will not play.  I am exporting the way the instructions on the help file correctly states.  But maybe there is something that I am missing.  Any ideas of what I might be doing wrong or don't understand. 
Never had this problem in Sonar Producer X3.
 
Midiboy47

Maybe it's a Win 10 problem.

midiboy1947
 
I am using Sonar 64 bit on a Window 10 64 bit. 
 

Please tell us this is not your production machine.....

I have Platinum installed on Win 10 pre-release but its NOT my production system.  I just have it installed there to see if or how it works. 
 
The latest pre-release version 10041 has caused regular PC audio problems for some. 
 
But using the pre-release (Beta) version, anything is possible and its strictly a user issue, not a Sonar problem.

What soft synth are you using? Have you tried with "Fast bounce" unchecked?
My first guess reading the post was you're using the MS Wavetable synth (as you gave no soft synth names). You can not export normally using it.

Thanks guys for the input.  What I am doing is I am transferring files from my old MMT8 machine to a normal midi file.  Which is great and I have about 300 compositions composed back then, but wanted to save to midi and clean up and use the patches from my Kurzweil Pc3X.   I bring the midi file into Sonar and clean it up and make the necessary settings.  But I didn't realize that on recording I didn't check the input box on the left at the bottom and the one's that didn't export correctly were the one's that had no setting in that space.  As soon as I put the input which is my sound card I quick having the problem.  
Thanks for the input. 
 
Midiboy47