This is really frustrating. I have tried every possible setting and it will not stop the armature from shifting position in pose mode compared to edit mode. I have not added weights and I have checked all of the axis of every bone and they are the same when I switch from edit to pose mode. When I attach the model to the armature it leans backwards every time due to the shift in pose mode and the back of the legs also get a slight backward curve. I have reset alt R and alt G in pose mode each time. The IK controller bone (bottom bone far left) is clearly causing the armature to leap backwards but none of the settings in the constraints fix it.