Be sure you don't have any ghosted/blank spaces in the Dep IP PIN box that might trigger a false message.

Could the Dep have been issued an IP PIN? The letter with it would have arrived back in January.  You may want the parents to see if they can Retrieve it online, just to be sure if one was issued or not

https://www.irs.gov/identity-theft-fraud-scams/retrieve-your-ip-pin#:~:text=If%20you're%20unable%20t...