Why isn't my cow spawner working?

[VisileZeik]

I've broken my cow spawner and put it back down, after noticing that when I placed it on the platform I made it wasn't spawning cows, and when I placed it down again I put it on grass but it still won't spawn any cows and the menu isn't helping at all

 

[xTheLintyStar]

The same had happened with me, you have to wait a little and get away.

 

[InkAsriel]

same here with my zombie spawner, it still isnt working sadly, but it did work a while ago

 

[Leroyy]

I've never seen this problem before. Maybe you should put these someplace else. They don't have room to groove. Or you could report this like a bugg.