White Boxes appeared on Illustrator file and they're uneditable

Hi there,

I’ve never come across this issue before, but when I opened my Illustrator file, a bunch of white boxes appeared. They’re uneditable, and I can’t seem to delete them. I’ve already tried expanding the appearance of the hills and rasterizing, but nothing works, the white boxes don’t become selectable or removable.

Do you know what might be causing this, or how I can fix it?