When I put a piston at y=0 facing the void and activate it, the piston extends, creating a block at y=-1.
To replicate, place a piston at y=0, facing into the void and the activate it.
When I put a piston at y=0 facing the void and activate it, the piston extends, creating a block at y=-1.
To replicate, place a piston at y=0, facing into the void and the activate it.
Thank you for your report!
We're actually already tracking this issue at MCPE-37825, so we will resolve and link this ticket as a duplicate.
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