Illustrator File Not Saving All Layer Data – Urgent Help Needed

Hello everyone,

I'm experiencing a serious issue with Illustrator version 29.4 on my MacBook Pro (macOS Sequoia 15.3.2).

I’ve been working for several hours on a complex file that contains around twenty layers, with a lot of text content on each. I saved the file regularly (every few minutes), but when I reopened it, I noticed that a lot of data from one of the key layers was missing—it was incomplete.

Strangely, I can still see the full content in the file preview thumbnail on the Illustrator home screen, but when the document opens, the information is gone.

Has anyone encountered this before?
Do you know how to recover lost content from a saved Illustrator file?

For context:

• I’m saving the file locally on my computer (not using cloud storage).

• My MacBook is brand new, very powerful, and Apple confirmed that it's not a RAM or performance issue.

• This is a critical project, and for now, I’ve continued working on a separate file. But I’ll eventually need to merge everything, which will be difficult since Illustrator is already lagging with just half the layers.

Any advice or tips would be deeply appreciated.
Thanks so much in advance!

Best,
Sonia