Welcome to the Forum. I suspect the problem is that the hedgehogs have become addicted to mealworms. Sadly that is not good news. Mealworms are actually not good for the hogs even though they like them. Not only are they not very nutritious, but they also have an imbalance of calcium and phosphorous, which can cause calcium to be leached from the bones of the hogs causing serious problems.
You really need to feed the hogs cat/dog or good quality hog food. Cut out the mealworms and the calci-worms. Not enough is known about calci-worms so they are best avoided – the jury is still out about them, so not worth taking the risk for the hogs when they aren’t necessary.
There is really no need to supplementary feed the hogs anything but cat/dog/hog food or cat/kitten biscuits. If they have become addicted to mealworms it might take them a few days to accept the cat/dog/hog food, but they will eat it if they are hungry. If you offer them mealwoms as well, they are very likely to choose those instead, so don’t offer them those at all. You might need to be firm with yourself if they initially refuse to eat the cat/dog/hog food, but if you stick to it they will eventually eat it if they’re hungry and will be the healthier for it.
It is better not to feed them supplementary food at all than to feed them mealworms. The natural food they can find for themselves would be much better for them. Making your garden more hog friendly is always a good thing to do, so that they can find more wild food for themselves. But it is important that you provide water for them all day every day.
Sorry if this is not the news you were hoping to hear. Good luck. I hope the hogs take to the new food soon.