The TurboTax update that I received yesterday seems to have fixed the IRA withdrawal taxation problem, at least for my situation (withdrawal from inherited IRA with no cost basis, no contribution or withdrawal from traditional IRA with a cost basis). Yesterday I had loaded my test return, but there was no change to the calculations, which initially made me think the update didn't fix the problem.
Today, to get the calculations to change, I had to edit the 1099-R in the Step-by-Step view (but no changes were made to the data inputs in the form), then go through all of the interview questions for this 1099-R as well as the final interview questions related to IRAs. At this point, the calculations were correct. I saved the file and reloaded it, and the calculations were still correct. In my case, this means that the entire inherited IRA withdrawal shows as being taxable on Form 1040 (correct), and that the basis in my traditional IRAs does not come into play regarding the taxable amount on the inherited IRA withdrawal (also correct).
