I'm creating some tracks that will be played as a loop in a video game.
Initially I bounced in WAV and I used Adobe Audition to convert it to MP3. In this case, the MP3 played perfectly, in a loop. No gaps. 
Afterwards I tried to bounce the MP3 file directly via Sonar (using the native MP3 and also the Lame MP3).
In both cases, the MP3 generated by Sonar presented a gap (at the end or at the beginning of the file, I can not say for sure).
The result was obviously an unusable loop file.
What could be wrong?
Why do Adobe Audition can convert an MP3 file correctly and Sonar can not?
 
If anyone wants to test, in this link there are two MP3 files, one generated directly by Sonar and another generated by Adobe Audition (after I exported the WAV file via sonar).
Initially they look identical, but if you turn on the loop function of your player, you'll notice that the version generated by Sonar has a gap when it goes back to the beginning. 
 

This seems to be a fairly convoluted issue because some players do it, some don't. 
 
This was most obvious when you had a live concert separated into cuts; there would be a gap between cuts. I would assume Adobe did something external to Windows to fix this. Windows 10 may have fixed it as well; I'm not sure. This thread may be helpful as it talks about solutions various people have found.

The MP3 format adds a short gap to the start of file by default as far as I know. This may have been overlooked.
 

I also tested on various players (VLS, Windows Media Player, etc) and both generate gaps, regardless of the file.
But one thing is for sure: if you listen to both files inside Adobe Audition, the MP3 generated by Sonar has gaps and the MP3 generated by Adobe Audition does not.
This is a fact.
But given this problem, I will no longer use MP3 for loops.
Thanks.

As I said... I assume Audition does something outside of Windows to fix the problem. I believe there's an Audacity plug-in that does the same thing.