All mobs sometimes glitch through the ground and players to. This doesnt happen to often but when it does its game breaking. This has only happened in realms that i know of
Comments 3
i can confirm that mobs will glitch through a block when taken out of a minecart sitting on the ground (not minecart rail)
Cleaning up old tickets: This ticket has not been updated recently (1 year+) so is being closed as Cannot Reproduce. If you feel this is still a valid issue then please comment, or create a new ticket following the Issue Guidelines.
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Does that happen only on a world reload? If so it's a dupe of MCPE-1982.