Scenario
Kit Components are not appearing on the Sales Order PDF Template even if theDisplay Components on Transactions has been enabled on the Item Record.
Solution
The preference of Display Components on Transactions is applied to the sales orders by the time the item is added on the sales order.
If the preference is not enabled by the time the item is added on the sales order, the components is not going to be printed on the form even if the item record has been edited and the preference for Display Components on Transactions is enabled.
To show the Kit Components, the item needs to be removed from the Sales Order (consider the related records already created before doing so) and then add back the item.