Rank 10 shipping drop rate impossible

I dont know what have you done or its just RNG but i am running 4 10th rank shipping crew and i can't get 2 more to make a proper shipment, its just RNG ?

As it looks like i've spend millions just to have the chance to get 2 more and i simply can't, can someone from the developers tell me if this is a bug or it's just pure RNG ?

Thanks

im in the same boat