It looks like there's a bug where artwork with a name that starts with an integer will appear to work fine until KgPanels attempts to render the artwork on the panel once it's selected.
Example: the other day I made background artwork that used a single digit for its name (e.g.: 1, 2, 3, etc.) would appear to work, textures would show up correctly everywhere, except when I actually selected that custom artwork as the background of a panel, the panel itself would not render the background texture properly until I deleted and recreated the artwork with the name "Artwork01".
If it is a bug, seems to be low priority, as it's really not that hard to use alpha characters in custom artwork names, but I thought that it should be noted in case others are running across this issue so they don't waste an hour or so trying to figure it out.