Sticky piston doesn't stick to a block when it's placed at y -63 coords facing upside.

1. Create a flat world
2. Place a sticky piston block facing up at y -63 coords.
3. Place a block 2 blocks above.
4. Activate the sticky piston and deactivate it

As you can see in my attachment, a sticky piston doesn't pull the block if it's placed on y -63 coords.