A native Add/Edit Form will always add a row or edit a row. Any ‘On Submit’ actions are extra after the row has been added or edited. I very rarely use the ‘On Submit’ action.
I think it would help to better understand what you are trying to do, and why you have an extra custom action ‘On Submit’. What are your custom action conditions checking for?
The fact that you have a Delete action immediately following an Add action, leads me to believe that something isn’t set up correctly.