If you have an amount in Box 5 of your 1099-R, you would report the amount when entering your 1099-R in TurboTax.
If your 1099-R is a CSF/CSA, the amount of your insurance premiums should automatically go to Schedule A, Medical Deductions.
If this applies to you, here's more info on How to Enter CSA-1099-R.
If you're using TurboTax Online, clear your Cache and Cookies and return to that section to step through the interview again to see if it resolves.
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