I said resistant to the force, not immune. Although I guess with Toydarians and Hutts it was specifically just mind tricks. In the EU there were all sorts of variations though. There was a species of lizard that evolved to be able to project a force neutralizing bubble around themselves because of a force sensitive predator on that planet. That same predator was later used by the Yuuzhan Vong to engineer the Voxyn, which were incredibly effective jedi hunters. The Yuuzhan Vong themselves were completely immune to the force, although the physical applications of the force worked just fine, like force lightning or throwing something heavy at them. I don't know if you could use force TK on one of the Yuuzhan Vong directly. There are also races, such as the geonosians, who are never force sensitive but the force still works ordinarily against them.
If there are races with an elevated tendency towards force sensitivity, it stands to reason that there could be all sorts of strange developments in the galaxy. Obviously the Yuuzhan Vong are a weird exception, but they're also extra-galactic invaders. This suggests that the power of the force is limited to that galaxy, that it might not work in the intergalactic gulf or in another galaxy, and that the Yuuzhan Vong might become force sensitive if they stayed in that galaxy long enough.
