When I press undo, the app crashes and takes me to the main menu.
In Progress
I use OPPO A3s. When I undo my work from doing a mistake, the app exits to the main menu. When I go back, all progress is gone (as they were unsaved). Please fix it.
The same problem 
Which app do you mean by 'the app'.
Please tell it.
Please uninstall then re-install to get the old working version again
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