I need help understanding the warehouses and supply chains of the Industries DLC

So I have both an ore industrial area and an oil industrial area. All the unique factories that require both oil and ore products are located in the oil industrial area and they often lack resources from the ore industry (picture 3) so I decided to build a warehouse with rail connection in the ore industrial area (picture 2) and a direct rail line to the oil industrial area (there is no outside connection). I set the warehouse with railway connection in the ore area to „empty“ hoping that trucks would deliver the ore goods (glass/metals) to the warehouse and they would then get sent off to the oil area by train. Instead I now have partially filled trains going in the opposite direction (picture 1) from the oil area to the ore area and I‘m just confused. Why tf would there be a train delivering ore products from the oil area to the ore area? At this point I‘m just shipping ore products in circles (to the oil area and back, there’s no outside connection to the train line and I’m not importing anything) while there‘s still a shortage of ore products in the unique factories located in the oil area. Can anyone please help me figure out what‘s going on and how to fix it? I just want to deliver ore products one-way from the ore area to the oil area by train.