Update: Found that every time the error occurred the log says :
LogPhysicsControlComponent: Warning: Failed to find bone data for upperarm_l
LogPhysicsControlComponent: Warning: Failed to find bone data for lowerarm_l
LogPhysicsControlComponent: Warning: Failed to find bone data for hand_l
LogPhysicsControlComponent: Warning: Failed to find bone data for upperarm_correctiveRoot_l
LogPhysicsControlComponent: Warning: Failed to find bone data for lowerarm_r
LogPhysicsControlComponent: Warning: Failed to find bone data for upperarm_r
LogPhysicsControlComponent: Warning: Failed to find bone data for upperarm_correctiveRoot_r
LogPhysicsControlComponent: Warning: Failed to find bone data for hand_r
LogPhysicsControlComponent: Warning: Failed to find bone data for pelvis
LogPhysicsControlComponent: Warning: Failed to find bone data for spine_02
LogPhysicsControlComponent: Warning: Failed to find bone data for spine_03
LogPhysicsControlComponent: Warning: Failed to find bone data for spine_04
LogPhysicsControlComponent: Warning: Failed to find bone data for spine_05
LogPhysicsControlComponent: Warning: Failed to find bone data for thigh_l
LogPhysicsControlComponent: Warning: Failed to find bone data for calf_l
LogPhysicsControlComponent: Warning: Failed to find bone data for ball_l
LogPhysicsControlComponent: Warning: Failed to find bone data for calf_r
LogPhysicsControlComponent: Warning: Failed to find bone data for ball_r
LogPhysicsControlComponent: Warning: Failed to find bone data for thigh_r
LogPhysicsControlComponent: Warning: Failed to find bone data for pelvis
LogPhysicsControlComponent: Warning: Failed to find bone data for thigh_l
LogPhysicsControlComponent: Warning: Failed to find bone data for calf_l
LogPhysicsControlComponent: Warning: Failed to find bone data for ball_l
LogPhysicsControlComponent: Warning: Failed to find bone data for calf_r
LogPhysicsControlComponent: Warning: Failed to find bone data for ball_r
LogPhysicsControlComponent: Warning: Failed to find bone data for thigh_r