The title is hopefully self explanatory. When a block is moved via its binding to a force relay, it does not interact with entities as if a piston had pushed it. This means that blocks pushed into mobs will suffocate them, lifts will not work, nor will any other frame machine that has to carry an entity. Oddly, this behaviour is also exhibited by the force relay block itself, when pushed by a piston.

This looks has landed in 1.14.x. MinecraftForge/MinecraftForge#5798 Is it worth reopening this issue?

that would only fix it for the relay itself, not for the moved block

Is that because there's no way to push a block as if by piston without a fake piston?

If you look closely, you can see the force relay isn't actually moved by the piston, it's broken and placed on the spot next to it. Here's why, there really isn't a way for blocks to detect when they're pushed by a piston, so I had to come up with a hacky way to get it to work. Calling this intentional for now until the piston move hook is added into forge.