Duplication of All Types of Rails With Pistons, Slime Blocks, and Observers

I was working on a 1.11 flying machine when I came across this bug. When I place the redstone block to activate the piston, and then remove it, the rail in front of the observer drops, but the rail still stays placed. This works for all rails and maybe other blocks I believe this might be because the observer has a 0 tick delay, and maybe the 0 tick delay is messing with the pistons a bit. Please fix this or my contraption might not work.

Thanks, Elliot.