Xpath Html Feed Importer won't create or update nodes programmatically but ok in standalone mode

I have set up a feed importer and used XPATH HTML Feeds Importer. The syntax is fine and it works like a dream when I click import myself manually then populates nodes, updates them no problem. However, it won't do this programmatically on a CRON job and I don't know why.

If I upload a bunch of URLs to the content type the feed importer is attached to it does nothing, despite the URLs being there and everything being fine. If i go to them and import manually, no problem at all! There is nothing wrong with CRON as it works perfectly well on XPATH XML feeds and some RSS ones on the same website. I have checked that I am using a unique field as well (that would actually show up on manual tests) and just about everything else I have seen on the forums.

I am close to tearing my hair out here, has anyone come across this same problem or have any suggestions of what I might be missing? When I look in the log I just see 'There are no new nodes.' But there are new nodes!