Thermite Grenade-Legendary tier 4 hero gear never drops for me. 1.5 years I have been doing special operations with aircraft hanger unlocked to allow tier 4 to drop in operations. 

I think 1.5 years and top 20 ranking for all time operations, realistically if random it should have dropped by now. I keep getting duplicates of all tier 4 legendary hero gear. But no Thermite Grenades EVER. It is highly suspicious and I am beginning to suspect it is purposefully being blocked to my account as a form of bait. 

Bait meaning to keep me doing operations and keep me playing the game and keep spending by forever making it unobtainable without my knowledge. 

Or it is a bug. And the Thermite Grenade hero gear is glitched to never drop for my account.