Assuming the payout was correct in 2019, I don't see an issue.
The 2019 RMD was done. The plan terminated as was converted into a DC account (an IRA) by 12/31/19.
For 2020, the RMD would be determined based on DC rules using the 12/31/19 balance. The DB influence has disappeared.
Since the 2020 RMD doesn't exist, no distribution needs to be made in 2020. Assuming they don't again change the rules, the 12/31/20 balance will be used to determine the RMD required for 2021.
Does anybody see it differently?
Larry.