Warden commendation not moving forward

My halo 5 warden kill commadation has been stuck on 7/10 for the last couple of months but have killed multiple wardens sense

In order for the kill to count toward your commendations, yours has to be one of the kill shots. If you do not get the kill shot your commendation count will remain the same. As you have noticed you can get a medal, but not get the commendation. The medal means you participated in the killing, the commendation means you actually killed him.