I do see another possible problem. The 60 day rollover option on Ameritrade's form says only one rollover is allowed per year (I assume that's an IRS rule) but I rolled over the remaining balance of the Vanguard 401k to Ameritrade last August. Hopefully, since I'm filing for an extension, all I have to do is wait until after the August date and do the rollover before the October 15, 2021 filing date.
