PyQt5 imported python page class window blinks(open and close) when linked

Question

When I generate the object of different class(Inherited QWidget) from active class, it just blink the called window. If I test calling window from imported python page(as a local run), it shows the complete window without an error of blink.

IPSettingWindow.py

app = QApplication(sys.argv)
ex = IPSWindow()
ex.show()
sys.exit(app.exec_())

Locally if we run , then it runs with above code(class object correctly get generated)

def LoadIPSettings(self):
    ipsw = ipsettingwindow.IPSWindow()     # object of class of imported page(getting failed , with a blink of window)

So , waiting for suggestions.