Piston stays open bug

What I expected to happen was...:
I placed powered redstone on a block of sandtone on top of a piston and I expected it to close when I broke the redstone.

What actually happened was...:
The piston remained open

Steps to Reproduce:
1. Put any piston anywhere and on top of it put a block such as sandstone in my case, and another block next to this sandstone.
2. put redstone on the block that is on top of the piston
3. put a lever in the one next to it to power the redstone
4. turn it on and break the redstone and the lever that were powering the redstone
– Doing that, the piston will stay on even with no power, when you break the block on top of the piston, it will close as it should.