I noticed that foxes don't have the hostility debuff that's in the "other sources" section of the resolve tray. However, I could not find this mentioned anywhere in the game, so it was confusing if this was intentional or a bug.
Finally, I found something official that mentions this:
"One of their most unique traits is their complete resistance to Hostility (they don’t get any Resolve penalty for it)."
Unless it's already there and I just didn't find it, this should absolutely be mentioned in the game somewhere, for instance under the Fox encyclopedia entry.