Maybe this is the problem... I reviewed my 2019 Return Form 8606 for comparison to my 2020 rejected Return Form 8606 (I had same type of Nondeductible IRA contributions and Roth conversions both years). My 2020 Form 8606 left line 15b blank (instead of indicating "0" like my 2019 correctly showed). Line 15b is part of the "Taxable Amount" calculation reported on 15c, so appears it needs filled in to be complete. An incomplete calculation could be the reason for the return to be rejected.
Line 15b seems to have something to do with qualified disaster distribution, so not sure why the rejection was coded "due to FED_Taxable_Inherited_IRA". I'm going to wait on the March 5th software update and check that line 15b on Form 8606 is filled in "0" before attempting to refile.
