Slime blocks don't retract with sticky piston going horizontaly west / east

Slime blocks don't retract with sticky piston going horizontaly west / east

What I expected to happen was...:
The piston was going to retract the slime block

What actually happened was...:
The piston didn't retract the slime block

Steps to Reproduce:
1. Make what is shone in one of the attachment picture and place a lever next to any of the redstones and turn it on and off.