There is a 100%-discount, service plan and plan rates have options "Show Zero Prices" set to "No". Will any order details be generated for purchases with this 100%-discount applied?
Order details will be generated for: - Sales Orders - Change Orders (resource upgrades) - Overuse resources fee in Billing Orders
No details will be generated for recurring fee in regular billing (=Billing Orders). Therefore, Zero Billing Orders will be generated which are not visible from the control panel.
The same algorithm is valid for the resellers transactions, 0-total transactions will be generated for sales and change orders and overuse in billing and no transactions will be generated for recurring fee taken with regular billing.
There is a feature request with id #PBA-80180 ("Zero price detail is created in all cases except recurring in billing order") to make this behaviour more consistent.