If traffic logs from Panorama have to be exported using the CLI export command, "Receive Time" have to be used as "end-time" and "start-time" but not "Generate Time".
In addition, "end-time" and "start-time" have to be equal to "Receive Time" (not less-than-or-equal or great-than-or-equal).
This is part of traffic logs with "Generate Time" and "Receive Time" columns:
If "Generate Time" is specified as "start-time" and "end-time", export will be successful but log will be empty: