Import_logs.py => URL looks invalid and is discarded

We are trying to get Matomo (4.0.3) to work with import_logs.py.
We have log processing working, and we are getting no errors reported on the logs.
However, the requests that we have in our logs (using --log-format-name=ncsa_extended and we have triple checked that our logs are indeed ncsa_extended) are not being identified or used. Every single visit, including root, is appearing as “Page URL not defined”

Having turned logging on, we get (as a DEBUG, even though shouldn’t it be a WARN?!) the message “WARNING: URL looks invalid and is discarded.” (This is from core/Tracker/PageUrl.php:359)

As this is import_logs, there are no cookies, so we have disabled “Do Not Track support” - but it has made no difference.

I modified the message to include the supposed invalid URL and I see a valid request:
WARNING: URL ‘/contact-us’ looks invalid and is discarded

So, is there a means of being able to prefix the request (eg via an option to import_logs.py or in config) or is this just a bug?

Okay, so the answer is this. Despite the flavour text on “Manage Measurables” saying It is recommended, but not required, to specify the various URLs, one per line, that your visitors use to access this website., import_logs.py will fail to generate correct posts without a url defined.