It is possible that rewards might not be added right away after completing them and take up to 3 days to be processed and added.
However, if you think that the reward should have been rewarded already, first of all, check whether the offer you have already completed is still displayed on the offer wall. On the offer screen, tap on the menu in the top left corner, select Reward Status, go to Not Rewarded and check what the status of your reward is.
The conditions for each reward are specific and need to be followed correctly. Creation of a new account might be required (you cannot use your existing progress in the specific game) or the game has to be downloaded using the link in the offer wall.
If there is a significant delay, please contact the provider about the offer that wasn't rewarded from their side.
Provider Contact Information:
Tapjoy offer wall - scroll down on the offer page to Contact Support.
Supersonic/Iron Source - report your issue at their email address firstname.lastname@example.org or tweet them at https://twitter.com/ironSource or @ironSource