Throwing a potion at the happy ghast with harness is ignored when it hits the harness.
Steps to reproduce:
Spawn a Happy Ghast
Give it a Harness
throw a potion ontop / sides
MCPE-201604
Ghasts and Happy Ghasts are not affected by splash potions that hit their top
Resolved
Fixed
0
(Unassigned)
1400976
Confirmed
Windows
W11 24H2
1.21.80.25 Preview
1.21.90, 1.21.90.23 Preview
Retrieved
This issue does not require a harness and is not unique to happy ghasts. If you throw a splash potion on top of a regular ghast it also does not get a status effect. What is going on is that splash potions affect mobs based on the position of the mob, not the collision box. The position of a mob is the bottom center point of its collsion box, ghasts and happy ghasts are 4 blocks tall, and the area of effect radius for a splash potion is about 3 blocks. Therefore, a splash potion that hits the top of a ghast/happy ghasts does not affect it.