In case anyone is interested, I discovered why I couldn't enter any information into Form 8889, it's because the 1099-SA form had not been entered. I had tried several times to "jump to Form 1099-SA," via a search from "step-by-step" mode, yet each time, TurboTax took me to Form 8889 in "Forms" mode. After repeated tries, on a whim, I right-clicked on the "Gross Distributions" field of the Line 14 Smart Worksheet, then clicked on "Data Source." Voilà, the 1099-SA entry window popped up. Once the 1099-SA form was entered, Form 8889 became responsive. As expected, the newly-completed forms didn't change the tax return bottom line, but now I am confident that all the required forms are completed properly. Thanks everyone.
