Funny thing for me on this it I also tried doing the same before finding my W-4 selection trick. I could not change the 2025 Withholding on the "Est Tax Option" form. It could not be manually changed. You are correct that this is what is keeping TT from creating the vouchers. It thinks I am already having withholding for 2026 that is greater than my estimated tax total. Buggy stuff here TurboTax.
