Are the requirements for the Treasure Raider achievement limited to one save/playthrough?

Question

Whilst playing through Far Cry: Instincts Predator I have been collecting the secret vials for the Treasure Raider achievement. I noticed that when you die and then reload a checkpoint the vial remains collected (i.e. doesn't reappear).

I was playing through the Jungle level and picked up the 3rd vial (outside the Japanese bunker). I died shortly afterwards, so when I respawned I returned to the area to find the vial was not available. I turned off the Xbox 360.

When I returned to the game, I continued towards the next vial. When I picked up the vial I was told that I had collected 3/5 vials for the level (I was expecting 4). I assume that somehow resetting the Xbox 360 meant I lost any vials I collected before hitting the next checkpoint.

My question is: Do I need to collect all vials on the same playthrough/save file to unlock the Treasure Raider achievement?

Answer 1

According to this guide:

They can be collected cumulatively through all playthroughs...

I also found that the author of the guide had the same problem, albeit on another level:

If you die after getting a phial and load to the last save point, it’ll still register that phial. Unless you make it to a further save point before shutting off your 360 though, you’ll lose the record of that phial and have to get it next time you play. I missed one on the second level due to this, so just be wary!