I'm trying to make a glowsquid farm with water elevators using soulsand in a checkerboard pattern on a 19x19 area that sends Squids from level y25 to higher levels into a killing chamber through a layer of scaffoldings. But when the squids reach level y65 to y69 they immediately teleport down to lower Y levels and repeat the cycle infinitely.  

What I expected to happen was...:
Glowsquids are supposed to spawn underneath the player's Y level and come up, pass through the scaffolding and stay on a higher level to be able to get killed by the player.

What actually happened was...:
Glowsquids reach the desired Y level and then get teleported back to where the spawning area is.

Steps to Reproduce:
1. On a warm ocean biome, dig a 19x19 area on y25
2. Make a checkerboard pattern with soulsand and a solid block on the entire 19x19 surface

3. On level y59 make a layer of scaffolding that cover the entire area. That is supposed to let mobs travel up but not downwards

4. On level y60 make a layer of water sources

5. Cover the entire area surounding the farm and player with non transparent blocks to allow glowsquid to spawn

6. Move the player to higher levels and lower till glowsquids spawn. 

7.Glowsquids will pass through the scaffolding as if it didn't exist and reach higher levels for a few blocks and then get teleported or moved quickly into lower levels to repeat the same movements in an infinite cycle or untill it despawns.