Please remember that when you buy the key for an expedition, you won't get the rewards until you collect the correct amount of the items that it shows the rewards for.

Example:

As you can see in this example you only have 135 keys so you won't get the rewards past that until you collect the 550, 750 and the 1000.

Once you buy a key you do not get all of the rewards automatically, you must collect the correct amount of items shown for the reward you are wanting.