Comment 1 for bug 1692070

Please can you provide more information?

Are these new files or ones that were previously thumbnailed OK by Files?
Where are the files located (does it make a difference). e.g. files on MP3 or some other locations may not thumbnail.

Is it only these three file types affected or are e.g. videos also affected?

Did this occur after a recent update e.g. to 0.3.4? Does it affect all views? Do the thumbnails appear if you hover over the icon?