why is the collections strategy not changing when an older invoice is paid

Summary:

I am using the Account Age of Oldest Overdue Transaction data point. I have a strategy setup based on the oldest invoice outstanding which starts with a friendly reminder, waits 15 days, then has a Past Due reminder and so on until it gets to a Termination. This is working as expected. However if during the wait period, an older invoice gets paid, I would expect the scoring to run again and see that the older invoice has been paid and the score is now higher so a different letter should be sent. However it doesnt change - the strategy