@winterescape
That can go either way......many valid 1099-R forms are generated and sent by various providers, with box 16 empty, even if $$ are in box 14 & a state in box 15. I have 3 paper 1099-R forms this year from 2 different providers. None of them have $$ in box 16, even though box 14 and 15 have entries.
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Why your import and paper copies from Vanguard differ from each other...is a puzzle though.
The tax "import" files have to be specially-formatted and perhaps the computer program that does that at vanguard has skipped box 16 for some reason.