[TWW] Riven Mod Challenge Won't Complete

[MegiddoRain]

My Rifle Riven Mod is currently veiled and it's challenge states "Maintain a x3 Melee Combo Multiplier (135+ hits) for 30 seconds while an active pet is present" and I've already checked if it unequips like everyone else reports and it doesn't, it stays there and the challenge shows up in game but I did it at least twice I'm sure and I didn't get it. I was doing a Dark Sector Infested Defense. I had it equipped to my Boltor Prime and my Dethcube Sentinel was present. What I'm really concerned with here is that my Sentinel is not considered a pet. If I find this is true I'm not going to be very happy as I have skipped getting the Kubrow module altogether. I've been playing since closed beta and have not liked the Kubrow since they were announced and therefore do not not want to be forced to get one to complete this Riven Challenge.