Droppers Receiving a Redstone Charge Won't Drop Items
Sometimes, when an upward facing dropper receives a restore charge, it will not move/drop the items inside it. As you can see in the screenshot below, there was an item placed in the dropper (inside the tower). The comparator is used to detect the item inside, and then power the dropper to move the item on upward. (I have used this method to design my own version of an item elevator). The only problem is, when the dropper was powered, the item did not move. As seen in the picture, the item is still stuck inside.
Environment
Minecraft 1.8.1, MacBook Air Mid 2012, 1.8 GHz Dual Core i5 CPU, 4 GB RAM, Java 1.6.0_ 65 64 Bit (From Apple for Yosemite), Intel Graphics 4000 HD Open GL Engine 2.1, OSX Yosemite10.10.1, Minecraft Launcher 1.5.3.
Created Issue:
Droppers Receiving a Redstone Charge Won't Drop Items
Sometimes, when an upward facing dropper receives a restore charge, it will not move/drop the items inside it. As you can see in the screenshot below, there was an item placed in the dropper (inside the tower). The comparator is used to detect the item inside, and then power the dropper to move the item on upward. (I have used this method to design my own version of an item elevator. The only problem is, when the dropper was powered, the item did not move. As seen in the picture, the item is still stuck inside.
Environment
Minecraft 1.8.1, MacBook Air Mid 2012, 1.8 GHz Dual Core i5 CPU, 4 GB RAM, Java 1.6.0_ 65 64 Bit (From Apple for Yosemite), Intel Graphics 4000 HD Open GL Engine 2.1, OSX Yosemite10.10.1, Minecraft Launcher 1.5.3.
Sometimes, when an upward facing dropper receives a restore charge, it will not move/drop the items inside it. As you can see in the screenshot below, there was an item placed in the dropper (inside the tower). The comparator is used to detect the item inside, and then power the dropper to move the item on upward. (I have used this method to design my own version of an item elevator). The only problem is, when the dropper was powered, the item did not move. As seen in the picture, the item is still stuck inside.

I had the same problem. I am running 1.8.1 pre-release 2 and in one of my redstone projects I powered the dropper and it didn't put the item into a hopper.
You do know that that setup will only work for one item at a time, right?
Are you sure you did put an item in.
The setup you have in the picture will lock in the "on" state if you put more than one item inside. Are you sure that's not what happened?