Took a day or two to realize that it was compatible with AC13 as well after I downloaded the Shape JM9 Label from the Object Directory and placed it in AC13. I guess what threw me off is that it was within a file migrated into AC13 from AC12 without unloading or detaching any libraries and showed up as missing in AC13.
Perhaps that one file had the label dragged and dropped in that one as opposed to being within a library. Anyway, I now have it as part of my main shared library and it appears in AC13 now.
A little
on my part