Nvgstcapture-1.0 can't preview image?

nvgstcapture-1.0 can’t preview image, but can save images, snapshots, and videos. Why?
nvgstcapture-1.0 --prev-res=2
The above command can run normally, but there is no graphical interface pop-up to preview, and no error is reported. You can enter j to save the snapshot. How can I solve it?
I use jetson-nano with imx219 csi camera

I have the same issue. I can see the stream using VPI Demos 1.0, though. Can it be the fact that I’m using VNC?