On the skull quest for Body Bags you need to finish with full heath. The last wave is two warrior choppers and a gunner chopper. The warrior choppers lower your health by 20 0/0. I kill the two warrior choppers first and this removes the gray bars in my HP scale. Next round I heal to make sure I am at full HP and kill gunner chopper but the skull doesn’t unlock. Is it a bug or am I missing something? I am at 926 skulls and this driving me crazy!