At the moment, it seems that any time you make any movement after hitting X to come to a full stop, hitting the additional command overrides your attempt to come to a stop.
As an example, if I hit X, and then want to pivot while standing in place, I'll begin to walk forward in addition to turning sideways.
Additionally, if I use my jump jets while standing still, once I land, I'll typically need to hit X, or I'll begin to walk forward.