In live, and in previous builds of IK 2.0 Beta, Seated mode would remember your height setting between avatars. So you would stay standing even though you were sitting.

In this build, switching avatar makes you crouch on the ground as if you went back to standing mode. But you're still in seated mode. So you have to click the toggle twice to put it back each time. This only happens when switching avatars, I did not observe it happening on any other action.