Cutting and pasting sync-locked tracks

I’d love to cut and paste sync-locked tracks (one is mono, the other is stereo), but when I try to do that, one of the tracks ends up being silent.

This is explained here, Audacity silences one track when both are pasted:

How do I cut and paste both sync-locked tracks, retaining the audio from both?

Thanks so much!

First, make sure you have selected in both tracks. That is, the grey selection region extends through both tracks. Do Edit > Cut.
Next, select the spot you want to paste to in the top track. Now here’s the trick: while holding down the shift key, press the down-arrow key - this will extend the selection into the lower track. Now do Edit > Paste.
– Bill

Got it, thank you Bill!!!