Adding an RMD should not increase your tax unless it is also generating a penalty. If you are using the software on your own computer you can switch to Forms mode and look for errors (highlighted with red !!!) but you can't do that with Turbotax online. If using online, you can call tech support, they can look at the internals of your file. But you might need to apply for an extension today so you have more time to get through tech support.
One thought would be to delete the 1099-R then enter it again. Enter it manually this time if you previously imported it. Trying answering that there is no RMD requirement.
You might also try deleting the 1099-R and enter it again using code 4Q for box 7 instead of Q. "4" indicates an IRA paid to a beneficiary. It's not clear from the instructions if 4 is allowed with Q, but you could try it and see if it helps. If not, delete the 1099-R and re-enter as-is.
If you leave the 1099-R off, you will probably get a bill for tax due. The IRS assumes all income is taxable unless you prove otherwise, and they will tax you even on a qualified Roth IRA distribution unless you list it on your return as non-taxable and sign your name attesting that your return is true and accurate.
