bulk apply item template

It seems we can only apply an item-template to an item from the GUI.
In many cases we need to apply a template to many items (1000 or more).

I tried with FBDI, but it only applies the template for NEW items. When using the UPDATE action, the template is not applied for us. Import process doesn't show any errors, it just doesn't apply the template.

The Manage Item page also does not seem to have a Mass Change action to apply templates.

Any advice on how to apply an Item Template in bulk?
From the Manage Item page or with FBDI.