Thank you for your feedback.
If you haven't yet, please update your device to 3rd Beta SW.
If the issue still persists, please use the latest Samsung Members app to submit an error report. You can use the following work-around if needed:
To solve the problem of Object eraser not working, you need to delete apps related to Object eraser.
※ How to delete apps related to Object eraser
Settings -> Apps -> Search( Keyword : eraser)
1) Delete 'Object Eraser' app
2) Delete 'Reflection Eraser' app
3) Delete 'Shadow Eraser' app
We appreciate your contribution to the Beta Program.
One UI Beta Team