Why isnt my ultraguage not picking up CEL's
 

So I decided to plug in my UG while at a light and drove around a good deal....filled up my tank and on the way home I put my cruise control on @35 while going over the bayonne bridge and my CEL light came on....car felt fine.

When I got home, I went into the menu and there weren't any pending or existing codes....I turned the car off and tried two more times....

This isnt the first time and it was one of the main buying points for me...

Any clue why this is?

I've cleared the code (battery disconnect) and am waiting to see if it happens again on its own, scanguage plugged in. Could the scanguage trip the CEL?