unless your return is rejected, you must wait until the original return is processed - you receive your refund or the IRS cashes the payment before you can file an amended return
I am in the same situation, my 2020 return is accepted but not getting my refund yet, shall i able to file an amendment? thanks a million!
WAIT ... the IRS usually catches this error. Amend later only if they do not catch it... you have 3 years to amend.