What happens if I modify the program / cardcode / tier/ rule / master reward?
The modifications you make on any Loyalty object are not retroactive: all the events with a date prior to the change wont take this change into account.
This is true even if theses events are imported after the change itself. The date taken into account here is not the creation date of the event in DB, but the value date of the event.
Example: a rule triggered by an order
Rule: if you purchase more than 100 euros, you get 1 reward
If you modify the condition to be 50 euros, all orders with an ordered_at date prior to the change and that are below 100 euro wont grant any reward to the member