On the GratisPay FAQ there is a topic about this, by the way:
So it is also possible that a) the partners are simply taking their time to give GratisPay an update or b) that there was an error from your side. So I'd suggest checking that again as well.I completed an offer, why is the status still "STARTED"?
Our partners inform us if the status of your offer is changed. With some partners it takes slightly longer for us to receive updates regarding the offer status. As soon as we receive new information you will be able to view that on your "My Offers" page. Of course, this may only happen if you have completed the offer orderly. Therefore, please, review the instructions of our partner again in order to ensure that you did everything correctly.
Best regards,
pearlbay