If Form 8889-T, TurboTax is stating I need to check the HDHP coverage check box (Line 1). I never had coverage at any point with an HDHP. Do I leave this box blank?

TurboTax has a design difficulty in the Review, in that it assumes that any taxpayer with a form 8889 must have HDHP coverage, which is why you are being asked to fill in this field on Line 1 for Self-only or Family. 

The design does not anticipate your situation in which you have a form 8889 because of your HSA distributions but never had any HDHP coverage.

The workaround in this case is to just check Self on line 1 of the 8889 so that you can clear the Review. You have already indicated that you had no HDHP coverage on Line 3 on the 8889, so all the numbers on the form will be correct - you are just doing this to bypass the Review.

You might make a note of what you did and why, not because the IRS will inquire, but because you may wonder next year why you did this...

Thank you so much! It allowed me through and I was able to file.