Hi Jason,
You should also make sure the annotate pdf cron job is running, and try uploading a brand new file that has not been uploaded before, many people have mentioned having issues re-converting previously failed files (for example from before the google converter was set up). Also the google API console has a dashboard and if the error is happening on the google side than you will see an error rate on the dashboard (although I have never seen the issue to be on the google side).