Holy giant block of text Batman!

I couldnt quite follow your entire scenario, I think you need to look at the 8812 and follow the math for the CTC/ODC credits and follow the math on the EIC worksheet to see how thats being calculated.

When you say you added a child and no change to the credits, did you mean no change to the refund , or no change to the credit showing on the 8812? (the credit is non-refundable, so it might not change the refund)