As well, I have found that sometimes, when an item is in the hopper, and the hopper is over a trapped chest (unconfirmed with a regular chest), the item can sit in the hopper while the chest is filled with the item. I.e. I have one piece of glowstone dust sitting in the hopper, and it is not being transferred to the trapped chest, but when I look in the trapped chest, it is slowly filling with glowstone dust as if the hopper were constantly feeding it.
Nathan Ell
As well, I have found that sometimes, when an item is in the hopper, and the hopper is over a trapped chest (unconfirmed with a regular chest), the item can sit in the hopper while the chest is filled with the item. I.e. I have one piece of glowstone dust sitting in the hopper, and it is not being transferred to the trapped chest, but when I look in the trapped chest, it is slowly filling with glowstone dust as if the hopper were constantly feeding it.