I setup a survey template that should be sent, when an Incident is closed.
I tested it and it worked fine. But since then, I do not get further surveys anymore.
It could that the option "Use Stricter Rules?" may have been ticked and therefore set to 'Yes' for the survey template.
This option prevents customers from receiving a survey they may had previously been sent. Unfortunately this information is missing in the "Help on This Window" menu selection.