If a participant appears in your data but not in "Awaiting Review" it is likely that the submission is "returned" or "timed-out". Please check in "All submissions" where you can manually approve these participants. If they can't be found in "All submissions" please get in touch. 

On https://beta.prolific.ac you'll see all of the submissions together including "timed-out" ones when you go to "View submissions" for a study.

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