I have been experimenting with a new piston elevator, however, I encountered an issue with blocks being pulled by a piston. When I have a piston facing upward attached to a slime block with a normal block beside the slime block, a player standing on the normal block will move up and down when the piston is activated and deactivated (see pictures 1 and 2); however, when the same set- up is reproduced with the piston facing downward, the player standing on the normal block can be displaced down when the piston is activated, but cannot be displaced up when the piston is deactivated (see pictures 3 - 5).

Essentially, a player standing on a normal block next to a slime block being pulled up by a piston will cause the player to glitch through the normal block and fall rather than be displaced up. The player is also pushed into first person if they are in third person after they fall through the block (I caught picture 5 at the very last second).

Steps to Reproduce:
1. Place a sticky piston facing downward at least 5 blocks above the ground. connect a slime block to the head of the piston. Place a normal block (stone, wood, dirt, etc) next to the slime block. Place a lever to activate the piston within reach of a player standing on the normal block.
2. Stand on the normal block and activate the piston. You should move down appropriately with the normal block.
3. Still standing on the normal block, deactivated the piston. Instead of moving up with the normal block, you will fall through it.

My hypothesis is that a deactivated piston does not affect player position. The reason that the piston facing up works is that when the piston deactivates, the player simply falls onto the new position of the normal block; but when the deactivation causes the normal block to move up, the player falls through the normal block instead. Perhaps there is some other issue, but this is my best guess.

Good luck, I hope you can fix it soon!