Form 2555 keeps erroring out, because I show "0 business days" traveled in the US, b/c this is true. The minimum required by TurboTax is "1." How do I fix this?

Please leave the field No of business days blank if you had 0 days on business in the US. Do not enter 0 as this causes the error.

Turned out I needed to leave both the No of business days AND the income earned in the US blank.