MW1 - Hammer Time quest bugged - not removing inventory upon completion

hexngone

As I have been completing the Hammer Time quest on multiple characters, I have been noticing that I find a stack of 25 Adamantine Plates +1 in their inventory after the quest is complete and they receive credit for MW1 (they accept the MW2 quest from the Artisan). At first I thought I was just confused with too many characters and inventory to shuffle. But the last three that qualified indeed have the stacks in their inventory (where they *only* had 25 Adamantine Plates +1 there before they turned Hammer Time in and completed it).

tldr:
Adamantine Plates +1 are not being removed from character inventory upon completion of Hammer Time quest