You cannot file as Head of Household if you have not entered a qualifying dependent, so the children must be entered or your filing status would be displayed as Single or Married filing separately. Check and see what is shown for your filing status.
If it is showing HOH, then something else has been entered incorrectly about the kids in MY INFO. You will need to go back through the screens for them --again-- and look to see if somehow the box for "invalid SSN" got checked, or see how you answered that weird question about whether they paid over half their own support -- you have to say NO.
Here is a grab from the same forms. There is definitely a problem. I'm super frustrated, I have been using TurboTax for over 10 years, and there really isn't much you can do to screw things up, but there is something wrong, and I don't want to have to pay anything more to have to speak with a live person to get it fixed.

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