Why does my saved Lightburn files disappear from my hard drive & external drive?

Hello everyone, I am having issues with saving large data files… This problem has occurred to me twice so I am seeking resolution here to avoid many hours of lost work editing data.

I am creating a huge project which contains 29 layers of various graphic elements. Each layer is about 15" W x 15" H. Total project length is 75" long x 15" H x 5.5" D.

About 30 sheets 3mm thick 16" x 16" plywood sheets will be used on this job.

I should had separated the graphics into mini files rather then everything on one file I guess…

Question:

Is there a limit of graphics data that Lightburn can handle? If so, what is that number / limitation?
How can I find my file which was saved various times during a 3-4 hour job of creating and editing nodes!!!

Any suggestions of where or how to retrieve the lost files from external drive and hard drive will be greatly appreciated.

Thank you!