Container: Item moves are not always detected/propagated

When working with Container.contentModel to display items, using something like an Instantiator or an intermediate model (eg. DelegateModel) doesn't properly sort the children when items are moved (eg. when using Container.insertItem(index, item) with index < Container.count). 

Or in other words, using eg. Repeater or ListView to display the Container.contentModel directly works properly (items are sorted correctly), like in the doc examples and in all the current Container-derived Controls.  But if you assign the Container.contentModel to a DelegateModel, then use the delegate model in the Repeater/ListView, the children are only sorted in the order they were added (or inserted), regardless of which order they're actually in.  Moving of items doesn't seem to be properly detected.

Same thing happens if using an Instantiator to create items, instead of a Repeater, even when the Intantiator model is set directly to Container.contentModel (no intermediate model).

Thank you,
-Max