Return rejected for "potential issue with the calculation of your Taxable Inherited IRA," but I don't have an inherited IRA.

I filed my return today, but it was rejected. The reason was "There is a potential issue with the calculation of Taxable Inherited IRA. I do not have an inherited IRA. I do have a traditional IRA and a Roth IRA. I use the backdoor Roth method, but my basis in the traditional IRA is 0. Why am I getting this error when I don't have a Taxable Inherited IRA?