I can see in the log that the "update" happens on schedule. It's just that if the IP hasn't actually changed then it doesn't update my service (dyndns). As I'm just using the free account it means that I am getting auto inactivity emails every so often.
Clicking the force update button means that the dyndns record is actually updated.

Any ideas how I can make sure the Dynamic DNS is updated regardless of whether or not the IP has changed?

thanks in advance.