Thanks again ...
Tested your icon (see attached) ....
I don't believe it's the image itself. I think it's the fact that the field should be a composite of both the image and the white box (for lack of a better expression). Note your last image posted with the style color background set to my color is fine, but the rest if the field it's sitting in is white. The icon pic actually seems to be "left justified" in that white box field?
Note the "Thanks" add-on mod graphic and its field right next to your mod. That construction is differently coded and the field consists of both the background box (link) and thanks graphic integrated.
Regards,
Badger