I'm genuinely not sure what the confusion is. I have not contradicted myself at any turn and don't know how to make explanation any clearer. I never said or determined the deduction could not be done, I said the program did not handle the deduction correctly, which is still the case.
To recap the situation again: my state tax withholding is >$15,750. TT appropriately recommended I take this as an itemized deduction on my FEDERAL return in light of the SALT cap being raised. I have no other amounts from other sources to itemize, my SALT represents the full amount of my itemized deduction. TT erroneously deducted this full amount as an itemized deduction on my STATE return as well, but state taxes paid obviously cannot be deducted from a state return. I posted because wanted to alert that this is a possibility using this service and I didn't know how to fix it. On my own, having received no meaningful engagement here, I determined that itemizing only SALT on my federal return, if properly handled, would result in an itemized deduction of $0 on my state return (must itemize state if federal is itemized), ultimately negating the extra federal refund I would receive by itemizing in the first place. Therefore, it made more sense to just take the standard deduction instead of spending more time on this. But I still thought it was worthwhile to alert about the error in case others experienced it.
So initially my aim was to get the problem fixed, and then I realized I'm my situation it wasn't worth it and said as much. I don't know how to explain it any better, but it's a moot point.
In checking the instructions for Georgia for filling out their tax return (link to GA DOR instructions for 2025 IT-511), Georgia does allow the inclusion of taxes withheld by Georgia as an itemized deduction.
Line 12a on Georgia Form 500 is the itemized deductions from Federal
Line 12b is an adjustment for income taxes other than Georgia plus interest expense for the production of income exempt from Georgia tax. If the only state tax was withholdings from income earned in Georgia, then this line would be zero.
Line 12c is the Georgia itemized deductions, which is line 12a less line 12b. Since 12b is zero, then line 12c would be the same as the Federal itemized deductions.