The 1099R doesn't usually (or ever, more likely) disclose the taxable event of 401k to Roth IRA. Obviously you still need to indicate that you rolled it into a Roth. A Form 5498 should disclose this (taxable) event. Form 5498s aren't themselves entered into tax returns, but the IRS gets them and would compare against the reporting of your 1040.
After you enter the 1099-R into Turbo Tax, you are eventually asked if you rolled it into a Roth IRA. You are asked this even if your code is a G. Ensure that you make this selection and are taxed on the rollover.
