https://twitter.com/SirMrDaisyBates/status/762842999189417984

Above is the video of it I posted on Twitter.

I was in the process of building the Iron Titan in my single player world. I built it to spec and followed TangoTek's 1.9+ updated design.

Using the original design, the dispenser seemed to fire correctly. Once I upgraded to the design he suggested for 1.9+, the dispenser would fire only one time after applying the redstone dust. After the very first time, it would never fire again despite it receiving a pulse. The interesting thing was, if I broke the dust and replaced it, it would fire correctly upon the next pulse, yet it would not fire again after that one time. The same was also true if I extended the redstone dust to the next block over (updating the dust that way seemed to make it fire successfully one time, then break).

I did my best to look over the build. I haven't seen any indirect powering or anything like that that may possibly lock the dispenser some how. I'm baffled.

I did do a fly around of it towards the end of the video. I receive the same results with or without optifine, so I do not believe it is a factor.