"Fill Right with Left"/"Fill Left with Right" Effects in Rush

Just ran into this problem on an edit, here's how I got around it:

1. Right click on the clip and select "separate audio". It will move the audio track to a new line.
2. Do that a second time, and it will duplicate the clip audio and put it on a different track.
3. Click the audio settings for one of the audio tracks, and scroll down to see the L & R waveforms. Click one and drag it into the other (for example, select the right audio waveform and drag it into the left and they will switch places).

That worked for me! As long as you have desirable audio on both tracks (like your left track doesn't have a totally different audio source and it's either empty or holds a safety channel) this was my work around. I hope it helps 🙂 Happy new year!