Child Tax Credit

[KNakohl7]

I received a letter saying I would receive the payments for my 12 year old, but haven't received any payment.

[VincentL12345]

A growing backlog of unprocessed tax returns now stands at 35 million at the IRS, creating ongoing refund delays for millions of taxpayers, the National Taxpayer Advocate said in a recent report. That represents an increase in the IRS' backlog of unprocessed returns from May, when it was holding 31 million returns.

We do not know how long it will take the IRS to finish its backlog of unprocessed return. The IRS has not provided a schedule to the processing backlog.

If you are expecting a stimulus check by direct deposit, check the IRS Get My Payment tool on the status of your check. You should also expect a confirmation letter from the IRS. You can also conduct a payment trace by calling the IRS Payment Trace tool at 800-919-9835 or fill out IRS Form 3133.

[Destiny_Y_JD]

If the payment has been issued by the IRS and wasn't received then you can request a payment trace. However, the amount of time needed to wait differs if you were receiving direct deposit (wait 5 days) vs mail (waiting 4-6weeks) to trace the payment.  
You can check if you re enrolled to receive payments and provide updated bank account information at https://www.irs.gov/credits-deductions/child-tax-credit-update-portal. I would start with the portal to see if the payment has been issued. 
You can check if you are eligible at https://www.irs.gov/credits-deductions/advance-child-tax-credit-payments-in-2021.