Half of my drawings suddenly gone and can't be seen anymore

I currently have my graduation work on Harmony 17 but tomorrow I’ve noticed half of my previously done drawings gone.

I can’t see it on the preview or render mode, it doesn’t appeal in small screen mode, but all files are saved. I didn’t delete anything nor move. This is the very first time I see this and honestly saying I’m in great panic rn.

I don’t want all my work to be gone. Please! Can anyone help me? I’ve noticed the same problem with previous versions of my project which I haven’t touched.

Is this a soft problem?