Ok i managed to fix it , so i followed some tutorial by unreal and they suggested to set focus on activate event. Because of this Set focus was calling twice.
So once it was set on [Self] because no buttons were created and once on the button. Because of this when button used to lose focus the main widget used to retain focus.
The reason why it didn’t in second try was because these buttons were already added hence focus to self was never executed.
Solution: Remove set focus “On Activate” Event.