Why is the medical payments I made in 2023 not deductible?

It depends. Many taxpayers don't get the benefit of their medical payments because of the adjusted gross income threshold on medical deductions, or the overall threshold on itemized deductions.

Return to the medical expenses section of Deductions and Credits and review the entries.

It could be that the total of the medical expenses you entered didn't exceed 7.5% of your Adjusted Gross Income, in which case you would not be able to deduct them this year.

It could also be that your total itemized deductions don't exceed the standard deduction for this year, in which case TurboTax would use the standard deduction since it was larger.

When you are using the Online version, it can also happen that there is a delay in your entries appearing due to Internet issues. 

You can also preview your return before filing to look at the forms TurboTax has prepared from our entries and find out how your taxes were calculated. See here for details. 

See this help article and this one as well as this tax tips article for more information on medical expenses and how to report them in TurboTax.