question

Given the error, it looks like you have a bad reference in the activity Travel to Rack. It says the operator label is pointing to Tools/ProcessFlow/ProcessFlow/Operator2. That's a reference to the shared asset resource not the 3D operator. Perhaps you typed 'Operator2' into the the Resource field and it linked to itself. I used the sampler and sampled Operator2 in the 3D view and it's now working correctly.

The Operator3 shared asset is also pointing to itself. If you sample Operator3 in the 3D view that'll fix that flow as well.

It looks like all of your flows are duplicated objects. You might look into either creating an instanced process flow (like a Task Executer Process Flow) or using a sub flow. With both of those options you can pass in or define variables to define different values (different racks, operators etc) for each flow. Then you only have one set of activities. You can even open a process flow view for each instance so you only see tokens associated with that instance. Check this page out from the user manual for more info on instances https://docs.flexsim.com/en/20.0/ModelLogic/AdditionalConcepts/ProcessFlowInstances/ and this page for sub flows https://docs.flexsim.com/en/20.0/ModelLogic/AdditionalConcepts/SubProcessFlows/