Generated HAR is not displayed correctly in HAR viewer



I am using mitmproxy v3.0.4 and generating a HAR file using the following:

mitmdump -n -r dumpfile -s "" --set hardump="ooo.har"

On opening ooo.har in any online HAR viewer, I see nothing, whereas there are entries in the HAR file.
On difference which I see between HAR files that show up correctly, is the absence of the pages key.
It is obvious that the has not chosen to set the pages key, any particular reason for that ? I can open an issue on Github, and possibly try to fix that.

As a workaround for that I tried stubbing some generic data under pages in, but still the HAR viewer shows it empty, maybe I have messed some timestamps etc.

But, anyways, what can be done in this case ?