@Just-Lisa-Now-  what's your opinion  -   I have similar situation unsure if I need to send Amended return. 

Client had 1099R distribution -qualifies for covid relief- did not want the 3year spread.  I sent return with F5329, line 2 exception 12.  This was before F8915 was available  and before I realized there was a check box to elect out of the 3yr spread.  (Yeah, I know - how did I not know...sigh)