Hi Rhys, I have completed numreous tests mate. They only work when the client doesnt click on the the link in the email straight away. Effectively allowing time for the deliver and open to update, before a click is made and then changed, triggering the workflow.
If a click is made before the email sent is created then no workflow. As you know the email send is created, then it takes about 2 minutes for the actual email to come through to say my hotmail as a test, then 4-5 minutes for the click to be seen or updated against the email sends/sent item, and then 2-5 minutes for the active sent email to be created which triggers the workflow.
This delay is causing missed triggers, if the active sent email creation already has a click or more than one click against the record.