I have a similar issue in 2020, receiving refunds for 2019, 2018, and 2017. Except none of them should be taxable because I didn't itemize in 2019 and in 2018 and 2017, I itemized but took the sale tax deduction instead of the State Tax deduction. So California did issue 1099-Gs in 2020 for refunds in 2018 and 2017. And I have to indicate that they are not taxable. It will not work if you put in 2019 first, it will only ask you about 2019. So I put in 2018 and 2017 first and it asked what part of the refunds were taxable and I put in zero. Then I went back and updated the State Refund part, adding the 2019 refund and it worked fine.
It took me awhile to figure this "need to put the older ones iin first, as I did have 1099-Gs for these years and couldn't reach around my elbow, but I kept trying as these posts made me hope it COULD be done, somehow. I hope this helps someone else.
