just enter the 1099-R as stated don't change the taxable amount to zero it doesn't mean that's your final tax due. There are supplemental questions after 1099-R entry where you can specify it was all converted to Roth.
Then the combination of the non-deductible IRA contribution and 1099-R will do the math on Form 8606 to determine the taxable amount is zero.
Follow these steps (with caveat a few steps for desktop referring to "What Did You Do With The Money From This Payer? screen." have still not been updated for the 1099R question changes - where it differs just follow what is on screen).
https://ttlc.intuit.com/turbotax-support/en-us/help-article/retirement-benefits/enter-backdoor-roth-...
