WidgetsBinding.instance.addPostFrameCallback((_) {
//setState((){});
});

또는

Future.delayed(Duration.zero, () async {

});

로 해결

if(position == widget.horizontalpageIndex) {
returnPadding(
    padding:constEdgeInsets.only(left:10.0),
    child: Column(
      children: [
        Container(
          child: feedbackModel.reversedListViewed[feedbackModel.reversedListViewed.keys.elementAt(widget.verticalPageIndex)][position] ?
          CircleAvatar(
            backgroundColor: Colors.transparent,
            backgroundImage: AssetImage("assets/teacher_1.png"),
            radius: 28.sp,
            child: Stack(
              children: [
                Visibility(
                    child: Container(
                      width: 55.w,
                      height: 55.h,
                      child: Center(
                        child: Icon(
                          Icons.play_circle_fill,
                          color: Colors.white,
                          size: 26.sp,
                        ),
                      ),
                    )),
              ],
            ),
          ) : CircleAvatar(
            radius: 30.sp,
            backgroundColor: Colors.greenAccent,
            child: CircleAvatar(
              backgroundColor: Colors.transparent,
              backgroundImage: AssetImage("assets/teacher_1.png"),
              radius: 28.sp,
              child: Stack(
                children: [
                  Visibility(
                      child: Container(
                        width: 55.w,
                        height: 55.h,
                        child: Center(
                          child: Icon(
                            Icons.play_circle_fill,
                            color: Colors.white,
                            size: 26.sp,
                          ),
                        ),
                      )),
                ],
              ),
            ),
          ),
        ),
        Expanded(
          child: Text('${position + 1}단계',
          style: TextStyle(
            color: Colors.white,
          ),
          ),
        ),
      ],
    ),
  );
}else{
returnInkWell(
    onTap: (){
      widget.onButtonTapped(position);
    },
    child: Padding(
      padding:constEdgeInsets.only(left:10.0),
      child: Column(
        children: [
          Container(
            child: feedbackModel.reversedListViewed[feedbackModel.reversedListViewed.keys.elementAt(widget.verticalPageIndex)][position] ?
            CircleAvatar(
              backgroundColor: Colors.transparent,
              backgroundImage: AssetImage("assets/teacher_1.png"),
              radius: 28.sp,
            ) : CircleAvatar(
              radius: 30.sp,
              backgroundColor: Colors.greenAccent,
              child: CircleAvatar(
                backgroundColor: Colors.transparent,
                backgroundImage: AssetImage("assets/teacher_1.png"),
                radius: 28.sp,
              ),
            ),
          ),
          Expanded(
            child: Text('${position + 1}단계',
              style: TextStyle(
                color: Colors.white,
              ),
            ),
          ),
        ],
      ),
    )
  );
}