Possible Bug at Mt Scarab RC

Having gone through the Mt Scarab RC a couple of times, in the Fight for Sanctuary DLC, to try and get a Hot Mama sniper I may have found a bug. After killing Lt Hoffmann a purple Vladov sniper usually drops. After picking this up the weapons never make it out of that mission,it must vanish in the Fast Travel ether. Is this fixable? It is a bit frustrating after going through the level to come out wih nothing. I am playing as Salvador at level 67 on PC

Unfortunately it is not fixable. The bug has been reported by various people (myself included), and applies to all platforms. Essentially, the sniper spawns with missing information so the game code deletes it at the first opportunity. (And the bug exists on all platforms.)