This is indeed a problem with our tracking software and should be fixed before Orion exits its beta phase. The problem is essentially that as the hand rotates, the estimate of the finger positions and postures changes and the virtual fingers move relative to the hand even though the real fingers don't. The problem is somewhat worse in desktop mode, but also occurs in HMD mode.
The main thing you can do to work around this problem is to use a liberal amount of hysteresis when releasing a pinch. In other words, say you start a pinch interaction when pinch strength > .7, don't stop the interaction until pinch strength < .4 (or whatever values that feel good). This is how our pinch detector scripts in Unity work, which is probably what you see in our demos. You could also potentially average the pinch strength over several frames, possibly only when the hand is rotating or moving rapidly.