A Form 1099-R does not indicate what type of account a 401(k) distribution is rolled to. If the Form 1099-R for the distribution from the 401(k) has code G in box 7, shows a zero in box 2a and the after-tax amount in box 5, the Form 1099-R is correct.
However, TurboTax does not gracefully handle split distributions. Enter the pre-tax and after-tax rollovers separately by splitting the Form 1099-R into two. (Another method is to enter the entire amount as having been rolled entirely to a Roth IRA and then indicate that a portion was recharacterized, leaving only the after-tax money in the Roth IRA, but 2017 is that last year that the recharacterization method will work due to the tax-law changes recently enacted that will result in changes to TurboTax for 2018.)
