Edit: After half day, my wife’s Mac started having the same problem. I have then applied the solution that I found in the Apple
Use Quick Look to Preview Files
Let’s say you want to find your childhood picture in a folder where lots of your photos are stored. It would be quite a tough task, just as looking for a needle in a haystack, if it wasn’t for the Quick Look feature of Mac OS.
Quick Look enables you to browse files — photos, videos, documents etc — without having to open a corresponding app. It’s quite easy to do:
1. Open the folder with the item you’re looking for.
2. Select an item and do one of the following actions:
a. Nlick the Quick Look icon (the one with an eye) in the folder’s toolbar
b. Press Command+Y on your Mac’s keyboard.
c. Press a spacebar on your Mac’s keyboard.
3. See the full preview of the item.
Quick Look keeps the preview window open, so that you can click the items until you find the one you’ve been searching for.