Why This Happens

Image thumbnails are previews of already edited photos. Luminar Neo uses cached data and indexing to display them quickly—especially in the thumbnail view. When the cache becomes too large or outdated, thumbnails may fail to generate or appear as black squares.

How to Fix It

You can clear Luminar Neo’s cache with a single button. Here’s how:

Windows

1. Open Luminar Neo
2. Go to File > Preferences
3. Find the Catalog cache size section
4. Click Clear cache

macOS

1. Open Luminar Neo
2. Go to Luminar Neo > Settings
3. Find the Catalog cache size section
4. Click Clear cache

After clearing the cache, you may notice a short delay when viewing previews of previously edited images. Luminar Neo will rebuild the thumbnails—this is completely normal.

You don’t need to clear the cache daily, but doing it periodically can help free up space and resolve black thumbnail issues.