I have a Samsung phone and I use the default camera to take videos. Then, in my home wifi, I transfer the files to my server using syncthing. The folders where these files are stored is then mounted on a different computer via lan (my main machine). The videos on that machine don’t always have thumbnails and I’m not sure why. How can I track that down? At what stage should the thumbnail be generated?

Technical information (based on questions that I am asked):

• The files are mp4
• I’m using kubuntu 24.10
• I’m using Dolphine file browser