I have experienced a buggy “Some things you can ask me:” (reached by tapping the question mark on the siri screen) for quite some time now. (> 6 months). I often found that the list was missing an application I had enabled to work with siri or was populated by one I had uninstalled previously. Now, no third party apps show up at all.
This is consistent across my iOS devices and has persisted through multiple phones, iPads, restores… nuke and paves… playing Mozart with the phone buttons to perform a secret reboot etc etc.
Any insight would be helpful.