There is a forum question , where user has stated that they have an RMA Order with Header level Invoicing and Order header workflow is stuck at the FULFILLMENT_WAIT_FOR_L( "Fulfill- Wait for Line") workflow activity.
Before I go to solution , I would like to add that when we use header level invoicing , Order header will progress to Invoicing and finally close only when all the order line are Fulfilled .To make sure that this flow work fine, Oracle has set up a Master Detail sort of relation ship between Order Header and Order Lines flow by means of some workflow activity.
In Order Header workflow for header level invoicing ,after Booking Order header workflow progress to Invoicing Subprocess , in Invoicing Subprocess there is activity "Fulfill-Wait for line", this activity will wait here till all the lines that are associated with the Order header workflow execute the workflow activity "FULFILLMENT_CONT_H" ( Fulfill-Continue header).Once Order /RMA line process execute "FULFILLMENT_CONT_H" ( Fulfill-Continue header) , lines informs the Order header about the progress , and once Order header receive this signal from all the lines associated with it progress to next activity (invoicing).
Now if you feel your Order header workflow is stuck at this activity "Fulfill-Wait for Line" , then there is fair possibility that not all the lines of this Order has Successfully progress the line activity""FULFILLMENT_CONT_H" ( Fulfill-Continue header)" OR there is fair possibility that you have associate a line flow without activity ""FULFILLMENT_CONT_H" ( Fulfill-Continue header)" at line .With out "FULFILLMENT_CONT_H" ( Fulfill-Continue header)" order/RMA line is progress and close , but Order header still waiting at "Fulfill-Wait for Line".
Please check both the cases and take appropriate action