If you look at the power company lightsource then you'll see that Alan is not an "invisible object" to volumetric lightsources.
He is not invisible to some, but is invisible to most light sources. His own flashlight for instance, doesn't cast any shafts when his arm is in front of it, but it does when any other object or character does (thats mostly noticeable when you got the strongest flashlight and has to climb some stairs with it)
Its just that very very few of them are actually capable of casting lights that create shafts. The safe havens creates shafts that keeps moving on its own regardless of what/where you try to block it with...this sometimes gives you an illusion that they react to objects. And most of the time the haven's lightsource is positioned in such a way that its impossible for you to block the lightsource in anyway.
Most of them are, but i remember a particular safe haven near a fence, and it did seen like the fence blocked the light... Tought that could've just be pre-calculated as the scenery does not move.
I'm not sure if it counts, but on last year's demo, they also had a safe haven stand in place where the elevator comes and Alan is attacked by birds, when the elevator is coming you can see the shafts... Its a shame the location was set up just for the demo, and ended up quite different in the game, but there's no change in sight from last year's demo aside from resolution...
I have tried blocking each & every light source found in this game with NPCs/other objects in the environment & apart from Alan's own flashlight, NPC flashlights & car headlights in 3rd episode and all of the power company lightsource...none are capable of casting dynamic shafts. And sunlight in this game isn't even a volumetric lightsource in the first place.
In chapter 5 or 6 there's a location where i believe was part of that Intel presentation, where they showed a garage door that opens showing volumetric light... That part seems to be in the game, and the volumetric light is there too, sure, its horribly low res, but its there.
About the company's light source, what you used to try to block the lights? I didn't noticed any particular object that could be both movable and close enough to try blocking with it XD
As for the sunlight, didn't early tech demos only showed volumetric light from the sun when it was about to rise or dawn? I didn't realy tried to see if its light was volumetric, so i can't really comment about that.
And sorry, but i didn't get this part: "apart from Alan's own flashlight, NPC flashlights & car headlights in 3rd episode and all of the power company lightsource...none are capable of casting dynamic shafts." Are you saying that those are the only light sources that cast shafts or that none of them casts?
P.S.[About Alan's hand not casting shafts from his own light, well if you look carefully then you'll notice that his hands don't create any shadows either....this is simply because his hands must be at a distance that's less than what's required for the flashlight to show any kind of interaction with a body]
Dunno about that, when climbing stairs i can see shafts from the stairs blocking the light and is more or less the same distance from the light as Alan's arm.