Hi there, I have built a ghast farm that transports ghasts from the nether to the overworld into a contained box environment. The box is one block thick - being made of a mixture of cobblestone slabs for the floor, cobblestone and glass blocks for the walls. I have tested my AFK spot in the nether for several different times - ranging from 30 seconds to 6 minutes. Basically it is luck of the draw if they stay in the build. With zero changes to the build they will either be mostly outside or all contained as they should be. I have tested just under 20 times and honestly about 1/3 of the time they stay in while the other 2/3 they escape. I am playing on a ps4 and mimicked the build in the following link https://www.youtube.com/watch?v=pLqZwmoKPF8