question

Part of the problem is TaskExecuterFlowItems do not have a Navigator assigned to them by default. In the Source's Use Transport logic, there is code that is telling the flowitems how to travel that does not require them to have Navigator and that why they can travel to the Queue. However, when the Travel activity is used in Process Flow, the Operators cannot travel the same way without a Navigator assigned. The other part is Operators are part of the Queue when they are travelling and they need to be moved back into the model before performing the travel task.

There are few ways to fix the first issue, however my suggestion would be to do the first one below as it is probably the easiest. For the second issue, you should probably just use the Move Object activity in Process Flow before the Operators are given a travel task. Just be sure to check the "Preserve Global Position" checkbox or else the Operator will "transport" to a different spot on the model grid during the move and it might look weird.

First, you could forgo using the Source in the 3D view and instead use Process Flow to create the TaskExecuterFlowItems using the Create Object activity. I would also suggest creating those objects in a Queue before using the Move Object and Travel activities.

Another option is to use a network of Network Nodes and connect the 3D objects to the network. If the Source is connected to a Network Node when the "Task Executer as Flowitem" option is used, then the Operators will be assigned the DefaultNetworkNavigator as their Navigator which the Process Flow will continue to use.

One final option I can think of is to use a Travel To Loc activity in the Process Flow instead of the Travel activity. This will give the Operators an Offset Travel task and that does not require a Navigator. You will need to give the X and Y coordinates yourself, but you can reference the Processor's X and Y coordinates for more dynamic logic.