If you have not been able to work with these client files, I would delete them. Be sure your current with updates on 2020 and 2021. Close both programs. Open 2020 and do the proforma again. Open 2021 and hopefully things will work well.

If they don't I am afraid you will need to make the dreaded phone call to support. https://proconnect.intuit.com/community/taxation/help/how-to-contact-lacerte-for-help/00/4691