Where does the Job-ID come from? If it comes from node “AddJob” or any before that will be the problem as expressions always reference values from the same “run”. Meaning the first time all nodes execute they are all on “run” 1. So it works. The second time PDF executes, this node is on “run” 2 and it tries to get data of “run” 2 of the node “AddJob”. That node did however only run once, so the value can not be got and it fails.
So for it to work, you have to make sure that the Job-ID is in the loop. You could, for example, add a NoOp-Node between AddJob and PDF and pass the Job-Id as data through all the nodes in the loop. Then you can reference the Job-ID from the NoOp-Node and it should work fine.