I'm having a hard time because the application suddenly went to the background.

Ladies and gentlemen,

Thank you for your continuous support.

I am troubled by the following events.
If you know anything, could you please let me know?

Launch the app

Operate the multi-step screen within the app

Tap something in the app screen (even if you don't have a tap event, etc.)

The app goes to the background and the home screen appears

It happens frequently on Android 6.
It doesn't seem to happen on Android 7.

If you need any information such as app configuration, please ask us.

*There were detailed steps, so I will add them below.

*For all activity calls, specify FLAG_ACTIVITY_REORDER_TO_FRONT

Thank you for your cooperation.