I found on the IRS page, they were talking about this change to the deduction, it seemed to imply you can either take up to the $300 deduction without itemizing your deductions, or you can itemize. I continued to receive the error if I put any amount in there and even if I left it blank, which I thought was strange. After reading what the IRS said, I went in and removed my itemized deductions and that seemed to clear the error with any amount put in 10a and 10b. It also did not change my refund amount like blanking it would have done. Even though it seems you have solved your problem, I am just leaving this here for others that face the issue.
