I am just exploring the world when I encounter an area that is just nothing. I can interact with things within the chunks, hit boxes even show up, but I am unable to see anything. I can see mobs, but not any kind of block or plant that naturally spawns. Can't see water (but I can still even swim in it...)
Just today while starting 14w29b I actually spawn on such an area. Mobs still spawned perfectly on it, but I could see underground ravines, mineshafts, caves, anywhere that had air. The blank areas never texture unless I reset the resource pack (wether it be Default or a custom resource pack). But then somewhere else or even the same place again, it happens.