[Mikuel]

I believe the issue is not that they are bugged but the fact they are "Gigas rex". Not "ancient gigas rex" which was the one that dropped dragon remains at bottom of the manor.

I could be wrong since has been while since I played my original chimera on the great six, but I do remember that you had to get to the VERY bottom of the area to find the gigas rexes those dropped dragon remains. All the floors before with gigas rexes only gave accursed remains.