Yes, this is some kind of "feature"IgorPobi said:I have one bug in RadioBoss 4.4. When prelisten output set to Stereo Split, this affected Broadcast streaming output !!! When prelisten, one channel go off on the broadcast !! I not tested RadioBoss 4.5 and not know about status of this error on 4.5 ....

For now, please consider it as limitation and don't use stereo split when broadcasting.
There are still other (and better) ways for prelistening:
1) use another sound card
2) use another channel pair on the same sound card.