Hi @shawkinson ,
This is because that you have used the Table function and that makes the screens become records in the table, so it won't be referenced to the screens inside the app.
Please use below formula instead:
If(ListBox1.Selected.Value="My Open Opportunities",Navigate(ScreenListMyOpenOpps,None),
ListBox1.Selected.Value="All Open Opportunities",Navigate(ScreenListAllOpenOpps,None),
ListBox1.Selected.Value="My Won Opportunities",Navigate(ScreenListMyWonOpps,None),
ListBox1.Selected.Value="All Won Opportunities",Navigate(ScreenListAllWonOpps,None),
ListBox1.Selected.Value="My Lost Opportunities",Navigate(ScreenListMyLostOpps,None),
ListBox1.Selected.Value="All Lost Opportunities",Navigate(ScreenListAllLostOpps,None))
Regards,
Mona