Hello Mine your Mind Team I started stoneblock 2 with an friend an we wanted to start the "roost" mod but after we placed a few (1 or 2) Chickens after that every chicken got "deleted". Dear Husky_Maze
This will happen if you have hit the mob cap for the area, this can be a combination of passive and hostile mobs in the surrounding chunks.
Also, Roosts themselves are limited. Only 3 per multiblock and a total of 80 allowed. So if you were placing roosts, and not plain chickens, you may have been trying to place a 4th Roost.