Prolific ID shows as completed, but not listed in actual dataset

New to Prolific here and running my first study! My first question in the survey is for them to copy/paste their Prolific ID. I’m noticing a handful of participants that say they are Completed (meaning they entered the correct completion code from the end of the survey) and awaiting review, but when I review my dataset in Qualtrics, there is no one that matches that Prolific ID (like, nothing close, not that they’re just a digit or letter off). Are these legit responses and I should approve them, or is this a red flag and I should reject them? Also, I need their IDs to be accurate as this will be a longitudinal study, so is there a way I can figure out who these people are in my dataset, if they are real? Is it appropriate to send them a message through Prolific to see if they somehow entered a wrong ID?