When using the production multiplier setting, the actual value of received items is multiplied by the square of the production multiplier instead of being directly multiplied, so a 50% multiplier leads to 25% items received, and a 10% multiplier only gives 1% of the items, while a 2x multiplier gives 4x

The displayed production when looking at the outpost on the world map is what it should be, leading me to believe that the multiplier is applied twice -- once when calculating the outpost's production, and once when actually sending the items to your colony.