Roth Rollover

During 2019 I made a rollover transfer from my IRA simple to a new Roth IRA.

I withdrew $30k, deposited $20k to the Roth and allocated $10k for taxes.

Schwab provided a 1099R  coded 7 IRA simple and when I enter that it enters $30k on the 8606 on line 7.

However, I cannot enter $20k on line 8 which I would think would subtract  from the above taxable amount and recalculate when entered as a rollover.

Much later, now, Schwab sent a form 5498 describing the $20k Roth conversion with no codes except

Roth IRA.

If I enter that  as a rollover amount below on form 8606 I will be taxed twice on the $20k.

Please help if you can