What I expected to happen was:
Piston extend and retract

What actually happened was:
Piston extend as it should. but it doesn't retract when the power turns of. The piston doesn't get a update when the redstone turns of

Steps to Reproduce:
Place piston
Place block on top of the piston
place 1 block next to the just placed block and at the back of the piston
Place redstone on top
activate the redstone

(see screenshots for better explanation)