I had the same issue of $0 taxable on SS income. I used TT online version and it was efiled. IRS caught it, fixed it, and sent me a notice. When I went back in TT to check, there was no question about being a US citizen. It asked, yes or no, if I was a resident of any of the foreign countries listed. I hadn’t selected either yes or no. Somehow I completed the return and TT said it found no errors.
