While some one else might have better diagnostic skills looks to help, here is some loss mitigation and prevention for you …
- Look for a recent .aia export file as a fallback.
- Keep multiple versions of .aia file exports.
- Keep block level .png downloads for all procedures and events, for incremental recovery via drag and drop into a fresh project screen.
- upload your .aia export file into https://unchive.kodular.io/build/ to see the blocks that AI2 could not load, to help you recreate them anew in a new Screen or Project. Unchive can see more blocks in your screen than AI2 can.
- Beware of unfiltered copy and paste into AI2 text blocks. They can corrupt a project.