TurboTax says I overcontributed to HSA in 2025, but I qualify for last-month rule and contributed exactly the limit

TurboTax is telling me I have an excess HSA contribution of $3,419 for 2025, and I’m trying to understand why.

Here is my full situation:

2024:

• I was covered under my parents’ family HDHP for all 12 months (Jan–Dec 2024)

• I was not claimed as a dependent

• I personally contributed $4,150 to my HSA (no employer contributions)

• My Form 8889 shows:

  • Family coverage all 12 months

  • Contributions: $4,150

  • Excess contributions: $0

2025 coverage timeline:

• Jan–Feb 2025: Family HDHP coverage (parents’ plan)

• Mar–Aug 2025: No HDHP coverage (Got a job and that job's healthcare plan was not an HDHP)

• Sep–Dec 2025: Self-only HDHP coverage through my new employer

• I had self-only HDHP coverage on December 1, 2025

2025 contributions:

• Employer contributions: $173

• Personal contributions: $4127

• No spouse

What I entered in TurboTax:

• 2024 coverage: Family plan for all 12 months

• 2025 coverage:

  • Jan–Feb: Family

  • Mar–Aug: None

  • Sep–Dec: Self-only

• Spouse coverage: None for all months

• Additional income under last-month rule: $0

My understanding:
Since I had self-only HDHP coverage on Dec 1, 2025, I should qualify for the last-month rule and be allowed to contribute the full self-only limit of $4,300.

However, TurboTax says my excess contribution is $3,419.

Questions:

1. Should I qualify for the last-month rule in this situation?

2. If so, why would TurboTax still show an excess contribution?

3. Is there a specific question or screen I may have answered incorrectly?