That is one of the list of generic reasons they give if they changed the Recovery rebate credit on line 30. How much is on 1040 line 30?
Do you have an amount on 1040 line 30 for the Recovery rebate credit? Did you not get one of the first 2 Stimulus payments? Or qualify for more? Line 30 is only if you qualify for more or missed getting one.
If you claimed a missing stimulus payment on your return but the IRS took it off you have to ask the IRS. They think they already sent it to you. Did you get the 2nd round after you filed your return? Maybe it went to an account you don't remember. Or you got a check or a card. It was probably easy to miss the debit card in the mail and think it was junk mail. They have to put a trace on it.
How to put a trace on a missing 1st or 2nd Stimulus payment. IRS for Payment Issued but Lost, Stolen, Destroyed or Not Received
See question F3 here, you can expand it to see how to put a trace on it.
https://www.irs.gov/newsroom/2020-recovery-rebate-credit-topic-f-finding-the-first-and-second-econom...
