Chickens stuck in cobblestone walls and cannot move away anymore

I have an enclosure with 10 chickens inside that I breed regularly to gather feathers as well as meat, but today as I bred them there were three of them stuck in the cobblestone walls on the each sides of the gate, and when I fed them with seeds the third of each group couldn't move to reach to other.

Plus, after the birth of young chicken from the other two adults of each group, the young chicken as well as the adults were attracted by seeds but couldn't move away from the wall.