Maybe not a solution for the problem itself, but s0undtv is a pretty good alternative to the official twitch app.
Yeah, I've been noticing this same issue ever since that Twitch update came out a few weeks back. As annoying as it is to force stop Twitch just so that I can watch YouTube videos, I was glad I discovered what was happening after only two days because I had at first been rebooting the unit whenever it happened ha ha ha.
Kowalski, translate!