(Form 2210) Annualized AGI Keeps Getting ZEROED Out by TurboTax and Underpayment Penalty Re-Introduced?

What is going on here?

 

I entered all my cumulative quarterly data for AGI etc. after entering my taxes. Turbotax wiped out the penalty. Then when I log back in the penalty is back. So I click into Other Tax Situation > Underpayment Penalties...

 

Not only is all the data I entered gone/blanked/zero but the final field (which is always pre-filled in by TurboTax and not user editable) says "zero" for my final AGI. 

 

I can re-enter my cumulative quarterly data. The penalty again disappears. But as soon as I leave the form, the penalty re-appears. Rinse. Repeat.

 

Any ideas why Turbotax keeps losing my data and re-introducing the underpayment penalty? Is there some 'trick' to getting it to actually save the form data that I'm missing?

 

See picture - that "Zero" for total AGI should be impossible.TurbotaxError.jpg