Good morning, I have a problem with the custom mission, I cannot complete the mission because the NPC has a bug. I have the cargo boxes in my inventory but it doesn't let me complete the mission.
Are you sure you didn't fail the mission before returning? Look at the success criteria listed by the npc.
if you still have the mission:
You need to go talk to a NPC in a red zone near another city, then you need to comeback to the original city where you claimed the pack to finish the mission.
If you don't have the mission anymore: you can only salvage the trade pack to get a part of the city hearts invested