Is my slug bait stale?

For decades I've used metaldehyde and found it very effective. Currently I set out homemade bait stations and put the material in when damage is detected. I'm using 3.5% pellets.

This year the control is not as good. I've lost some seedlings to slugs. Where I am it's been unusually damp and I did no till and thick mulching with fallen leaves. So that may be the problem. But I've noticed that the slug pellets have less of the characteristic cloying sweet smell.

Is my bait stale?