This is very easy to duplicate.
I have a collection called Websites with 3 fields: Name, Link, and an Icon.
The Icon is defined as an File/Image. Adding data to this collection works fine.
Including the displaying of the uploaded Icon image.
The problem occurs when placing a Data Table Element on a page.
In the Data Table Settings, I select the Collection and the Collection name.
But when I look at the Preview, the icon file name is displayed instead of the graphic.
The uploaded graphic displays fine in the Collection viewer, but not on the Table Element.