Finder preview not displaying thumbnails for JPG, PNG, PDF files
MBP 2021 running OSX 13.3, thumbnails do not appear for the subject files EXCEPT for those files stored in iCloud (not local). I've cleared QL Cache and the other recommendations from similar threads about this problem, rebooted to no avail. I do not have the Google Drive application so that possible issue is a dead end. I do have DropBox and tried one of the solutions recommended for DropBox finder integration, also no help.
suggestions appreciated