I assume the military has been lax on reporting crimes to civilian federal law enforcement because military officers, including legal officers, are concerned with the "up or out" nature of their careers- if they don't get promoted on time, they get booted. If they screw up the military-related legal paperwork of the members they prosecute, it could be a black mark on their record that could deny them a promotion, so they make sure it gets done.
However, there is no penalty to them individually for not reporting an ex-member to civilian federal law enforcement, so it's not high at all on their priority list to get it done. So, if the military wants to make sure that criminal activity by its members is reported to federal law enforcement, then they need to discipline the legal officers who fail to do it, starting at the top- the judge advocate generals. It may take some congressional intervention to force them to do so.
However, there is no penalty to them individually for not reporting an ex-member to civilian federal law enforcement, so it's not high at all on their priority list to get it done. So, if the military wants to make sure that criminal activity by its members is reported to federal law enforcement, then they need to discipline the legal officers who fail to do it, starting at the top- the judge advocate generals. It may take some congressional intervention to force them to do so.