The issue is you have the Park Points connected to the Control Points where items are getting unloaded (the ones connected to the Test Cells). That means the AGV will park right after it unloads an item and then it will wait for more work to be generated at the same control point where the item was unloaded. In this case, the AGV parks and waits for the recently unloaded item to finish processing before continuing on with the work loop.
If you want the AGV to listen for work after parking, then make sure it travels to the control point where the work is being generated, and then make sure there is a park point connection from that same control point.
Also, I assume you want the AGV to listen for when an item is ready to be picked up from a test cell, so you will probably need to make Work Forwarding connections from the control points connected to the work cells as well.
There are some notes that you may find helpful at the bottom of the section called Basic Parking (in the AGV with Basic Parking section) here:
https://docs.flexsim.com/en/23.0/WorkingWithTasks/AGVNetworks/UsingAGVProcessFlowTemplate/UsingAGVPr...