This was disabled in version of 1.02. However, it was re-instated in version 1.05 of the patch and is now working correctly.
Aside from the summons in your spellbook this feat also works with:
- the Negative Plane Avatar granted by death domain, or any creature summoned from an item (such as the Djinn from Storm of Zehir).
- Pale Master level 2 spell like ability, animate dead. (And assumed similar spell-like summons)
The feat does not work on Animal Companions, as Awaken is used instead.