I would imagine that they are getting eaten by rodents - mice, vole, squirrels etc.

There are many reasons why bulbs fail to come up. Often depends where you plant, how deep you plant and the soil conditions. Container planting would require that the soil be moist whether indoor or outdoor. The most likely reason if planted outdoors is that they rot before they emerge. This is when planted in sodden or heavy soil. Would require some grit in the planting holes so they don't sit in water that drains into the holes. Perhaps a little more information as to where and how you plant them.

Would also be useful to know whereabout in the UK you are... gives us an idea of climate and, possibly, soil type.

Which bulbs, precisely? And when do you plant each type of bulb?

Pardon my answer but you may be planting them upside down....all kidding aside dig the most recently planted ones up and if they are soft and mushy then JimmyT has your answer. If so, whether in pot or not, plant them in well draining potting soil.