As far as buggy achievements are concerned for this game, this achievement in particular is the most bugged and the most frustrating of them all for Dead Rising 3.
An effective guide has already been posted by
Ham Salad over at TrueAchievements. For this solution, I will give a quick synopsis of that post as well as the PC fix for the save solution. For the fully detailed solution for the Xbox One please see the following link:
TrueAchievementsThere are two possible bugs you can encounter when burning the 40 biohazards (both occurred during my first fun):
1) A random biohazard will not be marked on your minimap
2) Your in-game counter for this collectible will be stuck at around 35-38
As for #1, the locations of these unmarked biohazards tend to be random but have been most commonly found in the following locations:
- NW Ingleton (behind the house)
- N Almuda (in front the box truck behind the safehouse)
- Middle of South Almuda (very obvious on a sidewalk - in front of the fabric outlet)
- N Almuda (outside the Bus Depot)
- N Almuda (on a corner to the left of the entrance of the tunnel to Ingleton)
~Ham Salad
Out of both of these bugs, #2 is the most catastrophic as it will require you to delete your character (temporarily) and start the DLC over with a lvl 1 survivor. For the PC, this is a much easier fix than on the Xbox One.
1) Locate your gamesaves over at: (%USERPROFILE%\Documents\My Games\Dead Rising 3\saves)
2) Move your save files to a temporary, safe location.
3) Disable Steam Cloud Sync via Right-click on Dead Rising 3 (Properties/Updates)
4) Start Episode 4 again and progress until you unlock the biohazard collectibles and collect all 40.
5) Unlock your achievement.
6) Copy your old save files over your newly created save files.