DNG files not displaying thumbnail

Daymin said:

Oldnewexplorer might help with that.

.DNG ( Digital Negative ) is literally an international raw file type

Created by Adobe. It is enjoying more and more support amount photo editors, but not all editors support it.

to be used cross platforms without any discrimination. It's main goal is to counter Cannon RAW, CRAW2, and any other file time to prevent marketing of the RAW file only for Canon. SONY for instance uses the RAW format which in a nutshell is better.

This explanation is confused and confusing. There is no CRAW2 Canon file type. It is CR2. It's not intended to "prevent" Canon from marketing their RAW file type. Canon and Nikon both have proprietary RAW file types, and the marketplace seems fine with that. Back in 2006, a few people tried to get the camera vendors to support a common RAW file, but that effort had zilch impact.

For a non-destructive editor like Lightroom (not Light Room), the DEVELOP process consists of creating "instructions" for editing the RAW file for print, export, etc. In Lightroom, the original RAW file is never modified. With proprietary RAW formats, the edit instructions are store in the catalog and optionally in a sidecar XMP file. As you do more edits, only the XMP file chantges.

With DNG, the edit instructions are included in the DNG file itself. The advantage is that you don't need to use XMP files. The HUGE disadvantage is that a single edit change can trigger a backup of the entire DNG file. DNG files these days can exceed 50 MB. An XMP file is usually 1 or 2 KB.

When you shoot you shoot in RAW no matter the format. Always RAW because JPEGS are pugly garbage. Pop into Camera Raw via photoshop as a group/folder and edit/update etc. Same with Light Room

Poor advice for an events or sports photographer or PJ who might shoot thousands of photos but also needs to upload them on a tight deadline. In this situation, only JPGs are suitable.

A good chance you just should use the JPG as the reference, via the date number, and separate them into another folder.
I use "Irfanview" to organize my images, as it will open the RAW file as best it is able to and display the JPG thumb ( if one is present ) in the RAW file.

For someone like me, who shoots for pleasure and not for income, I have the time to process my photos through Lightroom (and Photoshop if needed. People like me shoot ONLY RAW. because the RAW file always has an embedded JPG, which is used only until Lightroom processes the RAW file.