The test for not being allowed to contribute to an HSA is whether or not you can be claimed as a dependent, not whether or not you are claimed as a dependent.
The US Tax Code in Section 223 says "(6)Denial of deduction to dependents
No deduction shall be allowed under this section to any individual with respect to whom a deduction under section 151 is allowable to another taxpayer for a taxable year beginning in the calendar year in which such individual’s taxable year begins." See US Tax Code Section 223.
Section 151 refers to the ability to take a dependent. Like much of the tax code, this is convoluted language, but it says (in translation) "No deduction for contributions to an HSA is allowable to anyone who can be claimed as a dependent by another taxpayer." It does not make any distinction for those who were actually claimed.
Therefore, TurboTax is handling the HSA contributions correctly.
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