Define "loosing". I have a rabbit I am going to shoot because he is obsessing on one of my Coral Bells and I am loosing the leaves to his digestive track. But if they are wilting and dying, check moisture level (I water mine) or possible a vole.

Like Cindy, there is a rabbit who has taken a liking to my heuchs this week. Vile creature.

Lack of moisture will cause leaves to go crunchy.

It is not a rabbit for sure .The leaves are drying out.

I'm having similar issues with some of my heucheras. The ones that have the dried up/burned out leaves are in more compact clay soil while my happy ones are in a much looser soil that has humus in it. Another issue can be from transplanting them, many of the leaves do dry out but new leaves will be forming from the center.