Box 2a on 1099R is not checked and as a result TurboTax is preventing me from e-filing. How can I resolve this?

[SweetieJean]

Box 2a is not a check off box.  Rather, it should be blank, say unknown, or contain a dollar amount.

If blank or unknown, leave it empty (do not enter a zero).

If you mean Box 2b, don't check off the boxes there unless they are checked on the 1099-R itself.

2020 Form 1099-R (irs.gov)