apple crumble for pie
Obviously I don't know your exact worker situation, but it seems like 5 minutes in advance for 1 person with a food processor should be enough to make more than enough 'crumbs'? This of course depends on your recipe for your crumbs, but if it's just rubbed butter and flour with salt, flavourings etc, it's possible to 'cheat' very effectively with a food processor.

In terms of chemistry, I'd guess your crumbs got too warm before they were cooled, so the fats in them had started to bond, and lumped together.