I figured it out. There was an error, but not on that line. I noticed line 1 of the worksheet form said ALL (a quote) the SSA-1099 forms for the earlier year plus the lump sum. It only had the lump sum for this year. TTax failed to import the SSA 1099 data for my income from 2024 1040 (line 6a), and when initially filling out the lump sum questions, I overlooked the box in the grid that should have had my 2024 benefits entered. Once I filled in that box the error went away, and so did my refund. Drat.
The error checking probably should have flagged both B and D since they are intertwined. This explained why 0 worked. The reason for the error should have been explained, not just a "check engine light". That would have saved me many hours and your time.
