In <i>The Three-Body Problem</i>, Liu Cixin describes the orbit of Trisolaris (Proxima b?) as chaotic. It's a major aspect of the plot. And this article references Barnes et al. (2016) for the hypothesis that "a passage of Proxima close to α Cen may have destabilized the original orbit(s) of Proxima’s planet(s)". That's pretty cool!
Summary: Proxima Centauri really does orbit Centauri A & B (which orbit each other as a binary system). Before now it was suspected that Proxima Centauri orbited the A/B pair, but the data wasn't completely convincing (it could have just been swinging by, since it's "orbit" takes 1/2 million years).