Thumbnails are not always displayed completely

If only the file icon of the associated application is displayed instead of the preview image of an image file, then an extension is probably installed on the system that cannot handle calls from multiple program threads.
In this case, you can configure SpeedCommander so that thumbnails are only loaded in a single program thread.

To do this, open the settings dialog and switch to the Advanced – Tweaks page. In the [ListWnd] section, set the MaxImageThreads entry to 1. After closing the settings dialog with OK and restarting SpeedCommander, the thumbnails should be displayed in full again.