I didn’t receive the child tax credit for one of my dependents but did the others. The child we didn’t receive the credit for we have guardianship of. We did file our 2020 taxes with her included.
Is the child related to you? If so, was the child age 16 or younger in 2020? Did you indicate that the child lived with you for more than 6 months in 2020?
If the child is not related to you then they Must have lived in your home for the whole year and are not eligible for the Child Tax Credit but are eligible for the Other Dependent Credit of $500.