How do I unlock new plane and rover contracts

I stopped receiving plane contracts. I am really far in the game and I still can't unlock runways and the port even though I unlocked higher technologies for planes in a tech tree, completed every tutorial and did all the missions that I had available in the contract feed now I can only do missions from the Professor. Contracts from Buck marshal with planes and rovers just stopped appearing and I can't go on. Can somebody tell me what exactly do I need to unlock more contracts?