Entities lose collision when in climbable blocks

What happens:

When mobs (Players, Villagers, Golems, Zombies, Creepers...) are in scaffolding, between two ladders or vines, they lose their collision with other mobs. Hitbox still works for attacks (punching, projectiles...)

Expected behavior: Collision inside of scaffolding should be the same like anywhere else (on the ground, in water, in the air...)

 

EDIT (21.11.2020): This also leads to maxentitycramming not working here, as no pushing can go on here, just like against ladders and vines.

Code analysis

Code analysis by [Mod] Avoma can be found in this comment.