The Bug
The Wither is no longer hostile to ghasts like it used to be in versions 1.13.2 and earlier.
How to reproduce
Summon a wither and some ghasts
→ ❌ The wither does not attack ghasts.
Linked issues
relates to 4
Comments 4
I can confirm this in 14w40a also I do believe this is a bug since Withers are only suppose to attack all non undead mobs and Ghast don't count as Undead mobs
Not sure if this is intended or not