Hi,
here is maybe a more reproduceable path to see the problem:
I use an simple application which switches between red, green, blue and white at a frame rate of 5Hz.
The display output is as expected (captured with a camera):
I then capture a video by using the gstreamer-pipeline from the post you mentioned: Zero-copy screen capture - #3 by DaneLLL
$ gst-launch-1.0 ximagesrc num-buffers=200 use-damage=0 ! video/x-raw ! nvvidconv ! 'video/x-raw(memory:NVMM),format=NV12' ! nvv4l2h264enc ! h264parse ! qtmux ! filesink location=a.mp4
This results in a video showing only the red and blue frames, and missing all the green and white ones:
Greetings!