CustomField does not get updated on initialization

i am not sure if this belongs here or in the components forum.
I have a custom composite field - composed of a ListSelect with a TextField and Add/Remove buttons below it.
When an item is selected, its caption will be copied to the text field;
When the remove button will be clicked, the item will be removed from the underlying collection;
When the add button will be clicked, a new item will be generated and added to the listselect.
It has to be generated, as the items ar actually pojos with several fields.
The text field also has an email validator (since items are identified by email addresses).

Now. It all worked fine when the whole thing was a CustomComponent.
The validator validated. My external method of adding this composite to a layout and then adding the collection to the component works (it just called addItems on the listSelect).

Now I tired changing it into a CustomField. I prefer it that way so I can bind it in the fieldgroup and update the underlying form data.
The field appears. But it never shows the items. I even added somne programmatically, and printed listSelect.getItemIds - and the are printed. But they don’t appear in the listSelect.
Also I noticed that the validator doesn’t work. It’s just an email validator added to the textfield.

I changed my creation code to create just a ListSelect instead of my CustomListSelect, and it seems to work fine.
Only extending CustomField causes these issues (extending CustomField, have a ListSelect Member and delegating all relevant methods to it - addItem/addItems most notably).

What am I missing?

Even if I just add the MyCustomSelect.getListSelect() the values appear.
It seems that when the list is just inside the CustomField it isn’t updated.