I just posted same question..did not see yours..apparently it may be a Proseries issue..I have a backdoor Roth with traditional nondeductible IRA..twice been rejected..

A forum in turbotax has the same issue..MArch 5th appears to be the timeframe when there may be a fix..link to the forum. I am following it and hopefully a resolution....

https://ttlc.intuit.com/community/retirement/discussion/federal-return-rejected-for-potential-issue-...