Any further ideas ?
If the reauthentication works and I can manually fetch the tweets, what is this leading towards. An issue with the CRON job itself, the config file not setting the secret ? The url callback is failing as well, so it's wrapped up in this somewhere.
Could it be something to do with the server set-up. Not sure what as I'm not a server guy, but I suppose I could ask the hosting company if they have any ideas.