I finally got it to go through.
First, you only file the 8812 if you have received the letter 6419 and/or a child tax credit last year.
What I end up doing to fix was going to forms view and deleting the 8812 with the "delete form" button.
Then I went back to step by step view, and went to my dependents, and put it order of the youngest to oldest. (no idea if it helped, but someone else told me to try it.)
Then I went back to the dependents section, and added in the ctc amount again and it worked.
No idea why
