"Hey Siri" feature turns off by itself
Hi, I own iPhone 6S Plus,
the problem I am having is that Hey Siri feature, turns itself off automatically, randomly. I always have to set it up after it`s disabled, and do those 5 hey Siri voice activation steps, it`s really annoying.
I found out it mostly turns off by itself when I restart iPhone, or make an iOS update. But sometimes it turns off even without those.
Please, can you assist me with this issue? It is really, really annoying.
iPhone 6s Plus, iOS 9.2.1