This is a TurboTax bug.
I get the same problem - simple 1099-R distribution that was rolled from a Traditional IRA to a Roth IRA. There was nothing to do with "2017 Disaster Distribution" (in fact it says I have "$0 as a Qualified 2017 Disaster Distribution" plus ":Pay tax on the entire distribution in 2018" checkbox).
I hope TurboTax is monitoring this tread and posts a fix.
