Make sure your priced items have due dates. For automations that are due before a payment due date, if that date has already elapsed, then the automation will not run. For example, if a payment was due today, it wouldn't run the automation set for 70 days prior to the payment date, because it has already elapsed.
FAQ
What if the due date is in the future but there's still no trigger date?
If your client has already authorized the payment, the reminder won't schedule a trigger date, even if the due date hasn't arrived yet. Payment reminder automations only look for payments that are still waiting to be authorized. Once authorization is in place, there's nothing left to remind about, so no trigger date appears. This is expected. The automation will fire on future trips where the client hasn't yet authorized by the reminder window.