If anyone else runs into the same problem, I was able to fix it by clicking through the "EasyGuide" to calculate my IRA basis and making some corrections.
Half the amount shows on line 4b. It shows the amount of the distribution minus my 2018 Traditional IRA non-deductible contribution, but if I put zero or $5,500...
Yes, after all the hurricane/disaster questions ("no"), I answered "Yes, I made and tracked nondeductible contributions to my IRA," entered my Total Basis as of...