Erratic publishing to Facebook

Not publishing reliably to Facebook. Found out this week that it had failed to publish since March – probably when I updated to the latest version. I have tried installing a new App on Facebook and switching to this but it did not help too much. Managed to force one article to be published by using edit > reload but this did not work for any of the others. We had issues with this particular site and Ultimate Facebook previously which were discussed on here, but it seemed to fix itself., Not sure what could be causing this – I run this plug-in on two other WP sites without any issues.