Dispenser Not Working

I have wired a dispenser to a button using redstone, and it will not fire.

I expected the dispenser to dispense or pick up lava each time the button is pressed.
What actually happened was the dispenser worked the first time the button is pressed, but needs a block update before firing again.

To reproduce:
1. Place a dispenser facing in any direction.
2. Place several lava buckets in the dispenser, along with one non-lava item. Tested with a gold nugget and lapis lazuli, with 7 and 8 lava buckets respectively.
3. Place a block above the dispenser.
4. Wire it as shown in the screenshot.
5. Place a button as shown in the screenshot.
6. Press the button twice.