8544 photos showing as not found on Mac ExFat external disk after folder relink, previews still visible in grid - (Photosdisk ># Lightroom Catalog > Mark > year folders). Have tried many times to find files with no success.

Another thing to check is if any volume, folder, or file name uses a character forbidden by macOS in those names, such as a colon. That might break links in some applications. The post title shows the # character, but when I tried that in a folder name it worked fine in a catalog (on APFS, anyway).

If no question mark icon exists on the folders, then my conclusion is that either the file name has been changed in your OS, or the file doesn’t exist in the folder you think it should be in. Please visually check your OS for these things.