In order to see thumbnails of your pictures in File Explorer, you'll first need to have the pictures available offline.
✔ Open your RushFiles drive in File Explorer and navigate to the folder that holds your pictures.
✔ Right-click the folder.
✔ Hover over RushFiles.
✔ Click on Download folder or Start synchronization.
✔ If you want to see previews of pictures on an entire share, then you can enable Start synchronization on a share as well, with the same steps.
Afterwards, make sure that files are shown as icons by File Explorer
✔ Click the "View" tab in File Explorer and you will see this menu:
✔ Highlight the "Large icons" option and close the tab again.
If you still do not see any thumbnails, do the following:
✔ Click the "View" tab in File Explorer.
✔ Click the "Options" button on the right and go to the "View" tab.
✔ Make sure the "Always show icons, never thumbnails" option is NOT marked.
✔ If you made any changes here, click Apply to Folders.