Opening large files created in the 2020 version gives a message " Illustrator could partially read this file. We recovered as much of the file as possible, but some content might be missing. Open to view the recovered file."

Any file with multiple layers or artboards only shows one artboard and layers are missing. The weird thing is the preview shows the full file and artboards, they just won't open.

Is anyone else having this problem? I've found that if you install illustrator 2020 and open it there it usually works (although not always)