How do I find what's wrong when one of my 1099-R forms keeps saying 'needs review'.

Delete the Form 1099-R and re-enter manually.  The problem should resolve itself.

Make sure that you don't have a zero in a field that should be left blank.

I am trying to enter a 1099r from American Equity Investment life ins co, it even came up for review, but it says it doesn’t recognize that co. I have deleted the one that came up for review and tried to enter as a new 1099r and have the same problem???!?

What finally worked for me was to enter a zero in boxes 16 and 19 even though the 1099-R had both of those fields blank.