I went to go call them again (to hopefully be a bit more aggressive about getting this fixed this time), and the contact us page suggested this page which says:
Some TurboTax customers are having issues with e-filed returns being rejected due to Foreign Tax Credit for US tax being withheld on 1099-DIV amounts received from mutual funds.
If you're experiencing this issue, please go here to receive notifications for any updates related to this issue.
It sounds like they are actually aware of the issue and you can sign up to be notified. That said, it also sounds like they don't have any idea why or any ETA on it.
