I tried to reproduce the problem with the provided information but to no avail. Here you can see a video showing RadFileExplorer behavior on our side: RadFileExplorer's file icons.
For your convenience I have prepared a sample page, could you please modify it to a point where the problem occurs and send it back?
In the meantime could you try resetting your browser settings to see if something there prevents the images from loading?
Thank you in advance for your cooperation.
the Telerik team
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