Using Kotlin reflection sealedSubClasses property in Android release build

When I am trying to use the sealedSubClasses attribute of a reified class in Kotlin, it only works in my debug and not in my release build. I guess this is a problem with ProGuard, but I don't know how to fix this. I already tried keeping all classes in the module where the sealed class is, but I am having no luck with this. The sealedSubClasses property always returns an empty list.