[Outdated][Bug 1.21] Slot stock too small(Fit door panels)

For (so far) one slot, the stock on the slot will be too small, so that it cannot hold the amount of products needed for two cars. This way, it has to wait after every car, since it will only order after a production is completed.
So far I have only found these:

Slot: Fit door panels
Product: Chip
Needs: 2 per car
Stocks: 3

Slot: Fit door panels
Product: Sensor
Needs: 1 per car
Stocks: 1

The slot will simply order no more products than these.
In a screenshot in a different game i noticed there this was not the case, so it is a bug that not will allways occur.
Anybody else seen this?
Thomas-save30-05-2017.zip (274 KB)