The alayavijnana and emptiness
Being empty is to be lacking inherent existence, which is to be lacking in fixed self, which is to be lacking in self. So a thing cannot be empty, and have a self, because being empty is to ultimately have no self, and all objects and phenomena are empty. It is not an either/or scenario, it can never be an either or scenario.

It is like asking if a canvass can be either paintless or blank. It is really a meaningless question, because it is just two ways of pointing at the same truth. It is meaningless to assert that paintless is either less or more substantial than blank. Is the son of a barren woman less substantial than the horns of a rabbit?

The karma is only as real and impactual as the blind attachment, and therefore assumptive delusion of self and true existence or true existential status. These volitional formations can be transcended in practice by developing equanimity, awareness, and insight