There is a defect in the case design. The charge pins in the bottom of the case move around in their holes. Making it difficult to get both buds to charge. Have to wiggle and press down on buds until they contact.
Have you made sure that the contacts on the buds and in the case are clean and free of any debris? A slightly moist Q-Tip should be able to remove anything interfering with good connectivity between the buds and the case.
