UI not properly updating after moving element from List<Widget> - flutter

Question

I have a List<Entry> mySet, which is a List of widget Entry.
In a parent widget, I use a ListView.builder to generate these widgets.
This parent widget has two additional methods
addEntry() {
setState(() {
mySet.add(Entry(index: mySet.length));
});
}
removeEntry(_EntryState entry) {
int index = entry.widget.index;
setState(() {
mySet.removeWhere((item) => item.index == index);
});
}
The buttons that call these in each entry look like this
IconButton(
iconSize: 25,
icon: Icon(Icons.add),
onPressed: index == mySet.last.index
? () {
setState(() {
pKey.currentState!.addEntry();
});
}
: null),
IconButton(
iconSize: 25,
icon: Icon(Icons.remove),
onPressed: isLast(() {
setState(() {
pKey.currentState!.removeEntry(this);
});
})),
And this function
isLast(Function fn) => index == mySet.last.index ? fn : null;
The condition on the add and subtract functions are identical, this was just me testing and trying to debug the problem.
The problem:
When I click to add a row widget, the prior rows' add/remove buttons are disabled, as they should be.
But when I click remove on the last row, the prior row's buttons are not re-enabled.
Yet if I make a small change to the code (anything), to trigger a hot-reload, the last row's buttons enable.
Here's my Listview.builder code, in the same parent widget.
#override
Widget build(BuildContext context) {
return ListView.builder(
itemBuilder: (BuildContext context, int index) {
return mySet[index];
},
itemCount: mySet.length);
}

Answer 1

The user in question Flutter: The widget values ​inside the ListView are not updated when an item is removed has a similar problem.
In your case you can solve this issue by using a ValueKey(property) where property is a a ofttribute your Entry object which you are sure is different for every Entry.
Make sure no two Entries can have the same value for property at the same time as otherwise flutter will throw an Error as you will have two identical ValueKeys.

Answer 2

I solved part of the problem by having one array that tracked instances of Entry, and one array to track corresponding states.
I could then call setState() for the last item which was the source of my trouble in my post.
removeEntry(_Entry entry) {
theSetStates.removeWhere((v) => v == entry);
theSet.removeWhere((v) => v == entry.widget);
setState(() {});
theSetStates.last.setState(() {});
}
If there's an easier way to get a list of instances of a Widget. Please let me know. Google didn't turn up anything.