My apologies if I am overlooking something obvious, but I've discovered that BusinessListBase subscribes to the PropertyChanged event notification of its children only in OnDeserializedHandler. New items added to the list are never subscribed.
I discovered this when trying to make a go of using the built-in indexing the class provides, only to discover it wasn't finding the new entries being added to the list if the indexed property was subsequently changed.
What was the rationale behind only hooking the existing child objects? Am I missing something?