You are correct regarding the expected tax treatment of converting non-deductible Traditional IRA contributions to a Roth IRA. However, reporting this in your tax return is a two-step process. You have entered the information from your Form 1099-R that reported the distribution. Now you need to enter the non-deductible Traditional IRA contribution.
Take a look at the following TurboTax help article for the steps:
How do I enter a backdoor Roth IRA conversion?
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