I think the title does a pretty good job explaining what it is, to recreate it, you go to y=1 and place a sticky piston facing upwards, then put a block on top of it, and toggle it using a lever (something else may work too). The block will get pushed up, but not pulled back down.
MCPE-123820
Upwards-facing sticky pistons at y=1 don't retract their block
Resolved
Duplicate
0
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We're tracking this issue in MCPE-96088, so this ticket is being resolved and linked as a duplicate.
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