I thought i had a good system where each outpost was only exporting 1 solid, 1 liquid, and 1 gas. This allowed me to isolate and sort at the receiving outpost.

The problem occurs when each outposts import & export containers get full. At which point materials flow from the export station, go to the import location where they can’t be unloaded, THEN THEY COME BACK to the original outpost where they get offloaded. You wind up with all the same materials filling both the import and export containers. Now the entire material flow is completely borked, nothing is getting imported, and all you have access to is the stuff thats locally produced.