Instead of just repeating the same answer that Line 4A can be blank, please actually read the 1040 Instructions regarding multiple distributions, which I have referenced repeatedly. Also actually look at the TurboTax "1040 Wks" worksheet and test whether Line 4 labeled "Pensions and Annuities" will pick up any number from its data source, which is Line 25 of the worksheet called "1099-R Summary".
Do some research, and stop dismissing this very real bug.
