This is not a bug. The auto recycle wasn't a feature. It was a required component because the player was unable to interact with the button due to networking limitations.
Could you expand on the "pausing" before they attack? If you've just joined this month, you may be experiencing the intermittent lagging introduced last update. It's something out of our control and will be fixed on the next forced wipe next week.
We're always improving our zombies though!
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