This suddenly changed for me from displaying a full-size image of files like PDF or JPG, to a small view in a box with a large file name.
Interestingly, spacebar to display a MS-Word .docx still shows the desired full-size preview.
One suggested solution said to Restart Finder.
I am going to try that but I am puzzled since it started occurring suddenly with no new OS or other software installed.
MacBook Pro 15″, macOS 10.15
Restart Finder worked for me to solve the small image preview of a PDF or JPG file.
To "Restart Finder":
Hold Option Key while Right-Clicking Finder in lower Control Bar.
Or Control-Option Key together while Clicking Finder in lower Control Bar.
Restart Finder appears at the very bottom of the list.
Restart Finder worked for me to solve the small image preview of a PDF or JPG file.
To "Restart Finder":
Hold Option Key while Right-Clicking Finder in lower Control Bar.
Or Control-Option Key together while Clicking Finder in lower Control Bar.
Restart Finder appears at the very bottom of the list.
Try booting into Safe Mode, then boot normally.
That can work as well.
Quick Look in finder only shows a small image
