Need to record additional mortgage interest due to a sale of our loan

After filing our 2024 taxes, we identified additional mortgage interest that we should have been included as a deduction (our loan was transferred late in 2024 and the company that our loan was sold to did not send out an annual statement). I assumed it would be a simple amendment to our taxes using Turbo Tax but when I enter the additional mortgage interest on our 2024 return, for some reason our tax amount owed goes up (vs. down). Does anyone know why this would happen?