ari444, I agree with macuser_22. For the distribution to have been a 2018 distribution you were required to comply with the processing requirements of the administrator which can include a reasonable delay in processing the distribution. Since the administrator did not process the distribution until 2019, it is a 2019 distribution, reportable on your 2019 tax return.
qofmiwok, the behavior of e-trade suggests that they believe that the account is not a solo 401(k) but is instead a traditional IRA, perhaps a SIMPLE IRA or SEP-IRA. If that's the case and they believed that you had done a trustee-to-trustee transfer of the account to another traditional IRA, it's not reportable and no Form 1099-R would have been issued. This is supported by the fact that they at one point issued a Form 5498 pertaining to this account. Presumably you completed and provided them with a signed 401(k) plan agreement, but perhaps whoever set up the account in the system created it as an IRA and not a 401(k) account. If it was in their system as an IRA, though, there is no way that they could have processed an in-plan rollover, only a Roth conversion from a traditional IRA to a Roth IRA. Are you sure that the account that received the rollover is a Roth account in the 401(k)? Regardless, there are no circumstances where a Form 1099-R is ever permitted to have code G in box 7, the IRA/SEP/SIMPLE box marked and anything other than a zero in box 2a and a zero of blank box 5. A Form 1099-R with code G in box 7 and the IRA/SEP/SIMPLE box marked indicates a nontaxable rollover from a traditional IRA to a traditional account in a 401(k) or similar qualified retirement plan.
