Retirement tax questions

@dmertz @macuser_22 thanks for the super thorough, helpful responses!

It was indeed a rollover into a 401(k). Separately from the missing 1099-R issue, is there anything else I need to consider to ensure that the return is prepared properly given that I’m filing two 1099-Rs in the same year? For example, I know that if I hadn’t done the reverse rollover prior to the backdoor Roth, that Roth conversion could be taxable (due to the mixed pre and post-tax funds that would otherwise be present in the Traditional IRA). How do I demonstrate to the IRS that I had emptied the Traditional IRA first? It doesn’t seem like the date of the reverse rollover and subsequent temporary balance of $0 is actually indicated on any forms in the prepared return? Very possible that I’m missing something simple and overcomplicating things.

FWIW, here was Betterment’s initial reply re: the missing 1099-R (I’ve since written back including the referenced IRS guidance):