Enter it the same as if the rollover was completed in December 2019. Enter the Form 1099-R exactly as received under Wages & Income (or Personal Income) -> Retirement Plans and Social Security -> IRA, 401(k), Pension Plan Withdrawals (1099-R) and answer the questions to indicate that you moved the money to another retirement account (or returned it to the same account) and indicate that amount that you rolled over.
