Thanks. I got through on the phone to the Oklahoma Tax Commission this morning, and despite their recent letter saying that the return "may not have been filed" (and threatening wage garnishment), they did actually receive the return and were simply holding up our refund. They say they sent a follow-up letter in 2020 requesting a copy of the W2 to verify identity, although we don't recall ever receiving that letter, and so they never sent the refund.
What a mess. Anyway, thanks for the help.
