Hey there. I built a mob grinder at y 256 and no mobs spawn from it. I’m on hard mode and 24 blocks away. Fix?
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Thank you for your report!
However, this issue has been closed as a Duplicate of MCPE-31323.
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Spawn radius reduces to none when you are near by Y:0 or Y:256. Were you standing 24 block away vertically or horizontally? Try 30 or more vertical. If it doesn't help. Try move grinder down little more.
I have reported a ticket about the y coordinate issue. It hasn't been responded by mods for a long while. I consider it WAI for the time being.