Dispensers and Droppers Don't Always Dispense/Drop Items

I made a capsule for my map and it has a couple dispensers going off at once and some command blocks too. Only the FIRST time you get teleported to the capsule, you get all the items. After that, you don't get all the items, unless you remake it. This is very frustrating and players in my PvP map never get all their items. I can't use command blocks to give enchanted things so I have to use droppers and dispensers.

You can look at the world save too. Just go to the coordinates: -1959.5 56 219.5. I have setup a capsule and and it should keep teleporting you into the capsule and you can see that the arrow doesn't dispense. It dispensed the first time I used it, but not anymore after that. It's always ONE item that you don't get. This bug needs to be fixed!