You mention "Lacerte/Tax20/IDATA" but you did not mention the drive. Make sure in 2020 that you look at Settings > Setup > Review the Data Path and verify it is the same drive you indicate data should go to in 2019.

Also check that you are on the latest update - Press F10 > look at Versions > 2020 Federal Tax = 41.0109

There are problems with 2019 and there is a planned update for January 7, 2021 https://proconnect.intuit.com/community/lacerte-tax-news-updates/discussion/organizer-issues-to-be-r...