Hopign someone could help me. Cannot see the thumbnails of jpeg files. Is there a setting I could change to enable this? On thumbnail view, all I see is the picture icon, no thumbnail, which is a bit odd.
Maybe there's a problem with your thumbnail cache.
Go to Preferences -> Listers -> Thumbnails and click the Thumbnail Caching Settings... button near the bottom. Verify that the path Opus is trying to store the cache in is valid and has disc space, and try clicking the button which clears the cache in case it's become corrupted somehow.