I noticed that for NPCs that use the "default" thumbnail will have that image rendered in the NPC tooltip:
But if the thumbnail is outlinked to another image, the NPC tooltip will not render the thumbnail:
This will be a bigger issue once other regions implement the new Canvas folders, since all of the default thumbnails will outlink to the Canvas folders (note the path Npc/_Canvas/2161012.img/info/default:
I noticed that for NPCs that use the "default" thumbnail will have that image rendered in the NPC tooltip:

But if the thumbnail is outlinked to another image, the NPC tooltip will not render the thumbnail:

This will be a bigger issue once other regions implement the new Canvas folders, since all of the default thumbnails will outlink to the Canvas folders (note the path
Npc/_Canvas/2161012.img/info/default
: