Not sure what your issue has to do with this Topic, but anyway…
Auto-Select is designed to open the Modifier Screen, which also happens to contain Portions (if any). By design, this screen will not close automatically - this is how it has always been.
If you want to add an Action to the Order Portion Changed Event to force the Order Tag screen to close, you could try Display Ticket Action with an ID of 0 (not blank).
On the other hand, if it is just Portions you want to look at for certain Items, without the need to open the Order Tag screen (i.e. do not use Auto-Select), you might want to set up the new features introduced in v4.1.78 …