[2021] Warlords of New York SHD Caches - is this a known glitch?

I have recently resumed playing The Division 2m, and acquired the Warlords of New York expansion.

Everything was going fine until I got the Civic Centre Liberation project - everything is complete save for collecting the SHD caches. One of the caches is in a sewer near the University. The idea is that I clear the first loot room, shoot a yellow power box to open the door to a second room, shoot the lock off the inside of the exit and then defeat a flamethrower-wielding boss, who is supposed to drop a key that allows me to access the room with the cache. Therein lies the problem - not once in eleven (as in the number 11) attempts has he dropped the damn key.

I am therefore unable to complete the Civic Centre Liberation project, which means I can't get the upgrade to the Haven settlement.