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)
Also works with other piston direction. Also its not a direction problem