Youre not completing the 8915E properly.

Open the 8915E.  Mark the box near the top that says Corona virus 2020 distributions reported in 2020.  Then scroll down to Line 12 (non IRA) or Line 26 (IRS) and put in your 1/3 amount of payment.  This will make the figures flow to the 8915F and the proper lines 4b/5b of the 1040.