New
#41
Do you mean on the PC where problem is ? ..... if so done that - no change
I changed default to 'snip & sketch'
Still no Thumbnails .... did confirm that double clicking on a DNG file opens it in 'Snip & Sketch'
Have you tried creating a new user account for test purposes and then in that comparing the behaviour of dng's?
That will tell you whether your perceived problem is something in Windows as a whole, or particular to your account, unless the problem comes from running the same program in both.
In the new user account simply use file explorer to check.