Get your taxes done using TurboTax

A 5498 is information  only and is not entered on  a tax return.

An Traditional IRA to Roth is a conversion that is taxable unless you had a non-deductible basis in the IRA.

The 8606 would only have a line 7 entry is you indicted that you had non -deductible basis in the IRA then it should have the $10K that was distributed and line 8 would have the $20K converted to the Roth.

Sounds like you entered it wrong.

Enter a 1099-R here:

Federal Taxes,
Wages & Income
I’ll choose what I work on (if that screen comes up),
Retirement Plans & Social Security,
IRA, 401(k), Pension Plan Withdrawals (1099-R).

OR  Use the "Tools" menu (if online version under My Account) and then "Search Topics" for "1099-R" which will take you to the same place.

Be sure to choose which spouse the 1099-R is for if this is a joint tax return.
Be sure to pick the correct 1099-R type: Standard 1099-R, CSA-1099-R, CSF-1099-R, RRB-1099-R.

If this was a rollover or conversion, answer the question that you moved the money to another retirement account (can be the same account). The screen will open up with choices of where it was moved.  Say that you did a combination  of things and enter the $20K converted amount in the bottom box.

[NOTE: When you get to the "Your 1099-R Entries" screen where you can add another 1099-R, use "continue" to keep going as there are additional interview questions after that screen in most cases. You can always return as shown above.]