WN 599G is a gas giant with high pressure. You need extra fuel to take off. Not a bug, you just need more fuel.
The normal solution is to contact the person you are shipping for and ask if they have some emergency fuel they can sell you. However, as you already have the shipment in your cargo hold, that won’t work because you have to buy the fuel into your cargo hold and then move it to your fuel tanks.
I think in this scenario you are going to have to either fly your other ship there with extra fuel and do a ship to ship transfer on the planet or hope that a Dev is willing to you bail you out on Monday in Germany.
Others may have different ideas.
Good rule of thumb is to always ensure you have extra fuel when traveling to a gas giant because takeoffs tend to be harder.