Some Redstone-based blocks (But most noticeably on Pistons) reacts extremely odd if it receives its power from a Redstone Block placed 2 blocks above it (MC-108).

It's difficult to explain fully, so I've made a short video of me experimenting with the bug, but a simple explanation would be that Redstone Blocks placed 2 blocks above (At least in my testing) Pistons are extremely unreliable, and require the player to manually give the Piston a nearby block update, whether that be placing a block, breaking a block, interacting with an entity etc. otherwise the Piston will sometimes extend itself without a power source.

I would further move to re-evaluate MC-108 (Specifically Redstone Blocks being able to power things 2 blocks below them), make it a bug, and fix it. Players are able to build devices in which pistons swap blocks between each other horizontally, but not vertically because of this issue.