I don't know if this has been added as a bug yet. Seems like it has been like this for quite a while. When attacked by a large mob, like a bear patriarch, my avatar won't fight back with auto-attack. It seems the center-of-(mass|model) is too far away for auto-attack to activate, but the bear is still able to attack the avatar. And it seems it is not just auto-attack but regular attacks as well. One needs to keep pushing forward to make sure ones attacks register, and for auto-attack to get a hit or two in as well, before the models adjust to put the avatar out of range again. Note: I am not talking about the knock-back that bears do now and then.