Switching animation only has 3 frames about flutterswitch HOT 1 CLOSED

Stack(
      children: <Widget>[
        Container(
          alignment: Alignment.center,
          child: _toggleAnimation.value == Alignment.centerRight
              ? _activeText
              : _inactiveText,
        ),
        Container(
          child: Align(
            alignment: _toggleAnimation.value,
            child: Container(
              width: widget.toggleSize,
              height: widget.toggleSize,
              decoration: BoxDecoration(
                shape: BoxShape.circle,
                color: _toggleColor ?? Colors.white,
                border: _toggleBorder,
              ),
              child: _icon,
            ),
          ),
        ),
      ],
    )