Notice that when placing down a factory, the number of resources sent is 2 times more than storage can hold. Example: The Electronics Factory has storage of 20 Iron and 20 Copper. There will be 20 trucks sent for Iron and 20 for Copper. Each truck contains 2 resources, therefore 40 Iron and 40 Copper resources will be sent. But the storage reports only 20 for each.
What happens to the extra/overflow resources.
This can be seen with other buildings and throughout the function of the factories.
It is like the reported ResearchLab and the SP1 Factory