I was working on a large file earlier this morning and, while in the flow of things, neglected to save the file.
SketchUp crashed and I went to my folder to grab the autosaved file but found no file saved there. I have autosaves from 2 years ago in the folder, but nothing from today.
Are you still using SU2018? Or have you upgraded to a newer version? If you are using SU2019 or 2020, this information might be useful regarding Auto Saves and saving of recovered files.