For some reason this happened to me at first too. As I played though, the dollar amounts DID catch up with me, possibly due to some server limitations for Contracts mode. It should fix itself hopefully
I figured that after every contract completed, you go back into the multiplayer menu and wait for the money to pop in before you proceed to the next contract, or else you don't get the money but the progress attempt and score was saved, wasting time and money.
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