When hit mobs may fall a block through the ground and will continue attacking, hitting the mob again fixes this. I have only seen this underground and falling through stone blocks
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migrated
MC-71921
Mobs can fall through blocks when hit
Resolved
Duplicate
0
migrated
migrated
(Unassigned)
Unconfirmed
Minecraft 1.8
Retrieved
This issue is a duplicate of MC-119. It has been linked to the original bugreport.
Please search before reporting any bugs, as it's likely that one exists already.