PyVista + Qt: Why does my callback only draw the 3d entities and not the 2d one on the second time?

[solarjoe]

Hello,
I have a question and hope that you can help me. I put together a small MCVE.
When you click the button for the first time,
you can see that the 3d (add_mesh, add_points) and 2d (chart.scatter) show up.
If you click it again only the 3d stuff shows up.
Do you have any ideas why?

import sys
import os
os.environ["QT_API"] = "pyqt5"

from qtpy import QtWidgets
import numpy as np
from pyvista import Chart2D
import pyvista as pv
from pyvistaqt import QtInteractor, MainWindow

class MyMainWindow(MainWindow):

    def __init__(self, parent=None, show=True):
        QtWidgets.QMainWindow.__init__(self, parent)
        self.frame = QtWidgets.QFrame()
        vlayout = QtWidgets.QVBoxLayout()
        self.plotter = QtInteractor(self.frame)
        btn1 = QtWidgets.QPushButton("Button 1", self)
        vlayout.addWidget(btn1)
        btn1.clicked.connect(self.buttonClicked)
        vlayout.addWidget(self.plotter)
        self.frame.setLayout(vlayout)
        self.setCentralWidget(self.frame)
        self.show()


    def buttonClicked(self):

        self.plotter.clear()
        data = np.random.standard_normal(size=(100, 3))
        actor = self.plotter.add_points(data)
        chart = Chart2D()
        _x = np.random.standard_normal(100)
        _y = np.random.standard_normal(100)
        chart.scatter(_x, _y, color="tab:blue", style="d", label="Scores")
        self.plotter.add_chart(chart)
        self.plotter.add_mesh(pv.Sphere())

if __name__ == '__main__':
    app = QtWidgets.QApplication(sys.argv)
    window = MyMainWindow()

    sys.exit(app.exec_())