This was a glitch on the 2020 software. Apparently it's still there for 2021. Use the work around, rather than trying to make the corrections in the forms/worksheet mode. Forms mode is not available in the online versions.
See the 2020 workaround at: https://ttlc.intuit.com/community/retirement/discussion/re-if-you-are-referring-to-making-a-qualifie...
