DNG files not displaying as thumbnails

[sargan]

W10 ver 22H2
If I go to a Windows 10 folder - all of the jpeg files with have a thumbnail (as do png, tiff etc)
Very few DNG files will have a thumbnail (usually none)

As folders may have hundreds of files - the thumbnail view is essential to quickly find files without having to open everyone.

Sometimes if I keep folder window open (active) for a long time a few of DNG files may change from default icon, but very few - this pic is an example.... the first file was default icon (no thumbnail for over 40 mins ... then finally a thumbnail appeared.



I have installed Microsoft raw image Extension .... v3 no difference
Have followed the steps to use CMD prompt to kill the thumbnail cache, delete it, and restart Explorer... all jpeg thumbnails rebuild (slowly) but not DNG.
Have also followed the tip in folder options - to uncheck 'always shows icons, never thumbnails' The advice is to click on the top button 'apply to folders' but I can't do that as that is greyed out (see pic)

 

[ChatGPT]

There are a few possible reasons why your DNG files are not displaying thumbnails in Windows 10. Here are some suggestions to try and fix this issue:
1. Install Adobe DNG Codec: By default, Windows does not have built-in support for DNG files. You can download and install the Adobe DNG Codec, which enables Windows to generate thumbnails for DNG files. You can find the codec on the Adobe website.
2. Enable thumbnail preview in File Explorer: Make sure that the thumbnail preview setting is enabled in File Explorer. To do this, open any folder, click on the "View" tab at the top, and make sure that the "Preview pane" and "Thumbnails" options are selected.
3. Clear thumbnail cache: In some cases, the thumbnail cache can become corrupted, leading to thumbnail display issues. To fix this, you can try clearing the thumbnail cache. Open File Explorer, click on the "View" tab, and then click on the "Options" button. In the Folder Options window, go to the "View" tab and click on the "Reset Folders" button under the "Folder views" section. This will clear the thumbnail cache and reset folder settings.
4. Rebuild thumbnail cache: If clearing the thumbnail cache doesn't work, you can try rebuilding the thumbnail cache entirely. Open File Explorer, click on the "View" tab, and then click on the "Options" button. In the Folder Options window, go to the "View" tab and check the "Always show icons, never thumbnails" option. Click "Apply" and then uncheck the same option again. This will force Windows to rebuild the thumbnail cache.
5. Update graphics drivers: Outdated or incompatible graphics drivers can sometimes cause issues with thumbnail display. Update your graphics drivers to the latest version available from the manufacturer's website.
If none of these suggestions resolve the issue, it may be worth considering using third-party software that specializes in generating thumbnails for various file types, including DNG files.

 

[sargan]

My phone creates DNG files direct .. my camera has to have file converted using Adobe DNG converter.
Just did a test and showed something I had not realised before.
File saved to Desktop ..... and it has the correct thumbnail.

When I move file to a sub-folder of My_Pictures it arrives there without a thumbnail.

Noticed another anomaly .... on my phone the selection is simply to output 'RAW' files.
They arrive on PC as filename.DNG

I just opened file with Mediainfo and it reports it as an invalid tiff ? (see attached)



I have wiped cache, increased the cache to 4MB, and rebuilt cache - still the same.
Here is a typical folder view ...


The DNG that have a block of solid colour, were just default, in time they sometimes then change to thumbnails