XnView Software

This is a known issue .
Thank you for pointing me to this older thread. From this thread I was able to find my solution for this issue:

Under "options->filelist I had to simply add mp4 to the video filter. After that the thumbnails got displayed immediately. So easy, should not be an issue to fix ...

I wonder if I am doing something wrong as I cannot see thumbnails of MP4 files in the browser.
All other thumbnails display well (mpg, flv etc.)

In Windows Explorer mp4 thumbnails are displayed. I have K-Lide codec pack installed.

I tried to search for a solution here but there are no results for ...