Bloodthirsty Medals- Problem

I just recently started a quest to achieve diamond camo on assault rifles and on several occasions I have noticed issues involving the camos that require a set amount of bloodthirsty medals. I usually play Chaos Moshpit to try to grab quick kills and as most of you are aware, the objective based game modes are in this playlist. I have found at least 5 times recently that if I end one round with 4 straight kills and then get a kill in the next round to earn a bloodthirsty medal, it does not count towards my camo. I have made sure that I only use the gun and I do recieve the bloodthirsty medal, but the number for the camo does not change. Is this a glitch? Does anyone else have this issue? I cannot come up with any logical reasoning besides it may be a mess up.

P.S. This problem has occurred mostly in Domination for me.

As mentioned above, all kills are achieved by using only the weapon, but the problem persists.