I've just been starting work on a creeper farm and playing around with this, and after looking at issues and screenshots posted here and doing some testing, I don't think there's a bug.
@Wormbo 's comment also points this out - but in all of the situations screenshotted, bar 2019-06-30 11.20.45.png, the creepers do not have a valid spot to pathfind to.
In my testing, some things that were causing problems and solutions:
Testing on a glass platform. Glass blocks were not working as a solid block for creepers to pathfind to, and thus they were unable to run away from cats.
Built spawning platform out of slabs. Again these were not valid solid blocks for creepers to pathfind to, and thus unable to run away.
Some issues I can see in screenshots posted here:
No solid block on the other side of the trapdoors for the creepers to pathfind to. In some screenshots there is just void on the other side of the trapdoor, some a solid wall, and one has glass blocks topped with carpet. Creepers can't pathfind to any of these positions.
George Cowie
I've just been starting work on a creeper farm and playing around with this, and after looking at issues and screenshots posted here and doing some testing, I don't think there's a bug.
@Wormbo 's comment also points this out - but in all of the situations screenshotted, bar 2019-06-30 11.20.45.png, the creepers do not have a valid spot to pathfind to.
In my testing, some things that were causing problems and solutions:
Testing on a glass platform. Glass blocks were not working as a solid block for creepers to pathfind to, and thus they were unable to run away from cats.
Built spawning platform out of slabs. Again these were not valid solid blocks for creepers to pathfind to, and thus unable to run away.
Some issues I can see in screenshots posted here:
No solid block on the other side of the trapdoors for the creepers to pathfind to. In some screenshots there is just void on the other side of the trapdoor, some a solid wall, and one has glass blocks topped with carpet. Creepers can't pathfind to any of these positions.