Today, Jan. 15, I received a letter and "EIP Card" from the Dept. of Treasury via a private company, "Economic Impact Payment Card, PO Box 247022, Omaha, NE 68124-7022. (It could have passed for a bill or junk mail, although there was a note on the envelope that it was neither).
I activated the enclosed debit card and the balance contains the rest of the stimulus payments that were due. Much relieved.
My best guess is that these funds could have been offset for anything other than a stimulus payment (student loan debts, etc.) and were diverted to a card-based payment for... reasons.
So CHECK YOUR POSTAL MAIL VERY CAREFULLY.
More info here: https://www.eipcard.com/
Also here: https://www.irs.gov/coronavirus/economic-impact-payments
