Restoring Thumbnail Previews in macOSRevisionas of Tuesday, 13 January 2026 at 18:47 UTC

Got generic-looking icons instead of previews for MP4 files and couldn’t figure out what was going on.

Tried Finder → View → Show View Options → Show icon preview to no avail

Then force quit com.apple.quicklook.ThumbnailsAgent in Activity Monitor and relaunched Finder. All was well.