How to activate the mob spawners in the latest Pixelmon mod for Minecraft?

In Pixelmon 4.0.6, for Minecraft 1.8, I came across a dungeon underground in my single player world and it had a spinning pig in the spawner. It didn't spawn anything though. In 4.0.5 I had the same issue but I remember in even older versions spawners would still spawn mobs. Is there any way to activate these spawners? Also, the server I play on has active dungeon spawners. I use a Mac if that effects anything.

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