Good catch, Base 57. Obviously, anything routed to a nonexistent device is going into the bitbucket.
 
However, the original assertion that the export does not rely on the audio interface remains valid, insofar as the interface has no bearing on what the exported audio sounds like. Whether you have a $7,500 Lavry or a $10 Realtek you'll get exactly the same results when exporting. 

scook
Try increasing BounceBufSizeMsec in Preferences > Audio > Configuration File
 

 
Just to clarify why this works, the default value of zero for BounceBufSizeMsec in tells SONAR to do offline audio processing using the buffer size currently set for the audio driver. So even though SONAR isn't actually using the interface to generate audio, changing the buffer size for the driver affects offline (a.k.a. Fast Bounce) rendering as well, and some plugins can get unhappy with Fast Bouncing at low buffer sizes.
 
Setting a non-zero value for BounceBufSizeMsec overrides the driver setting with a larger value for offline processing. Values from 20 to 200 (milliseconds) are reasonable, and may speed up processing as well as eliminating glitches with some plugins.