When dragging custom mime data then it will not show a drag image to represent the data

When dragging custom mime data then it will not show a drag image to represent the data, for standard data such as URLs it is fine, but with custom data it will end up not having anything set. In the attached example, if you drag from the left view to the right once then it is fine as it is dragged as URLs, do it a second time and there is no image as this time it is done as custom data. When debugging it seems to match the custom data (since it has 2 entries on the pasteboard) to be a url based type even though that is not the case.